diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetControlFlowBuilder.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetControlFlowBuilder.java
index 31bfcec6ce7..7870411aa85 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetControlFlowBuilder.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetControlFlowBuilder.java
@@ -10,7 +10,7 @@ import java.util.List;
  * @author abreslav
  */
 public interface JetControlFlowBuilder {
-    void read(@NotNull JetExpression expression);
+    void read(@NotNull JetElement element);
     void readUnit(@NotNull JetExpression expression);
 
     // General label management
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetControlFlowBuilderAdapter.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetControlFlowBuilderAdapter.java
index 0c6ea512103..01894b01598 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetControlFlowBuilderAdapter.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetControlFlowBuilderAdapter.java
@@ -13,9 +13,9 @@ public class JetControlFlowBuilderAdapter implements JetControlFlowBuilder {
     protected @Nullable JetControlFlowBuilder builder;
 
     @Override
-    public void read(@NotNull JetExpression expression) {
+    public void read(@NotNull JetElement element) {
         assert builder != null;
-        builder.read(expression);
+        builder.read(element);
     }
 
     @Override
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetControlFlowProcessor.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetControlFlowProcessor.java
index d9897b438d8..12fee5b0ec3 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetControlFlowProcessor.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetControlFlowProcessor.java
@@ -746,6 +746,7 @@ public class JetControlFlowProcessor {
             if (subjectExpression != null) {
                 value(subjectExpression, inCondition);
             }
+            boolean hasElseOrIrrefutableBranch = false;
 
             Label doneLabel = builder.createUnboundLabel();
 
@@ -753,11 +754,18 @@ public class JetControlFlowProcessor {
             for (Iterator<JetWhenEntry> iterator = expression.getEntries().iterator(); iterator.hasNext(); ) {
                 JetWhenEntry whenEntry = iterator.next();
 
+                builder.read(whenEntry);
+
                 if (whenEntry.isElse()) {
+                    hasElseOrIrrefutableBranch = true;
                     if (iterator.hasNext()) {
                         trace.report(ELSE_MISPLACED_IN_WHEN.on(whenEntry));
                     }
                 }
+                boolean isIrrefutable = JetPsiUtil.isIrrefutable(whenEntry);
+                if (isIrrefutable) {
+                    hasElseOrIrrefutableBranch = true;
+                }
 
                 Label bodyLabel = builder.createUnboundLabel();
 
@@ -770,17 +778,22 @@ public class JetControlFlowProcessor {
                     }
                 }
 
-                builder.nondeterministicJump(nextLabel);
+                if (!isIrrefutable) {
+                    builder.nondeterministicJump(nextLabel);
+                }
 
                 builder.bindLabel(bodyLabel);
                 value(whenEntry.getExpression(), inCondition);
+                builder.allowDead();
                 builder.jump(doneLabel);
                 builder.bindLabel(nextLabel);
                 nextLabel = builder.createUnboundLabel();
             }
-            // TODO : if there's else, no error can happen
-            builder.jumpToError(null);
             builder.bindLabel(doneLabel);
+            if (!hasElseOrIrrefutableBranch) {
+                trace.report(NO_ELSE_IN_WHEN.on(expression));
+            }
+            builder.stopAllowDead();
         }
 
         @Override
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetFlowInformationProvider.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetFlowInformationProvider.java
index c0284d377b5..f5b5f06dae2 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetFlowInformationProvider.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetFlowInformationProvider.java
@@ -74,7 +74,7 @@ public class JetFlowInformationProvider {
         wrappedTrace.close();
     }
 
-    private void collectReturnExpressions(@NotNull JetElement subroutine, @NotNull final Collection<JetExpression> returnedExpressions) {
+    private void collectReturnExpressions(@NotNull JetElement subroutine, @NotNull final Collection<JetElement> returnedExpressions) {
         Pseudocode pseudocode = pseudocodeMap.get(subroutine);
         assert pseudocode != null;
 
@@ -85,14 +85,14 @@ public class JetFlowInformationProvider {
                 @Override
                 public void visitReturnValue(ReturnValueInstruction instruction) {
                     if (instructions.contains(instruction)) { //exclude non-local return expressions
-                        returnedExpressions.add((JetExpression) instruction.getElement());
+                        returnedExpressions.add(instruction.getElement());
                     }
                 }
 
                 @Override
                 public void visitReturnNoValue(ReturnNoValueInstruction instruction) {
                     if (instructions.contains(instruction)) {
-                        returnedExpressions.add((JetExpression) instruction.getElement());
+                        returnedExpressions.add(instruction.getElement());
                     }
                 }
 
@@ -122,7 +122,7 @@ public class JetFlowInformationProvider {
                 public void visitInstruction(Instruction instruction) {
                     if (instruction instanceof JetElementInstruction) {
                         JetElementInstruction elementInstruction = (JetElementInstruction) instruction;
-                        returnedExpressions.add((JetExpression) elementInstruction.getElement());
+                        returnedExpressions.add(elementInstruction.getElement());
                     }
                     else {
                         throw new IllegalStateException(instruction + " precedes the exit point");
@@ -138,7 +138,7 @@ public class JetFlowInformationProvider {
         JetExpression bodyExpression = function.getBodyExpression();
         if (bodyExpression == null) return;
         
-        List<JetExpression> returnedExpressions = Lists.newArrayList();
+        List<JetElement> returnedExpressions = Lists.newArrayList();
         collectReturnExpressions(function.asElement(), returnedExpressions);
 
         boolean nothingReturned = returnedExpressions.isEmpty();
@@ -155,7 +155,7 @@ public class JetFlowInformationProvider {
             trace.report(UNREACHABLE_CODE.on(element));
         }
 
-        for (JetExpression returnedExpression : returnedExpressions) {
+        for (JetElement returnedExpression : returnedExpressions) {
             returnedExpression.accept(new JetVisitorVoid() {
                 @Override
                 public void visitReturnExpression(JetReturnExpression expression) {
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/JetControlFlowInstructionsGenerator.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/JetControlFlowInstructionsGenerator.java
index 71d5ffc290e..0425c7d2403 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/JetControlFlowInstructionsGenerator.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/JetControlFlowInstructionsGenerator.java
@@ -227,8 +227,8 @@ public class JetControlFlowInstructionsGenerator extends JetControlFlowBuilderAd
         }
 
         @Override
-        public void read(@NotNull JetExpression expression) {
-            add(new ReadValueInstruction(expression));
+        public void read(@NotNull JetElement element) {
+            add(new ReadValueInstruction(element));
         }
 
         @Override
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/Pseudocode.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/Pseudocode.java
index f9e1ea2ded1..b4565b36517 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/Pseudocode.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/Pseudocode.java
@@ -33,7 +33,7 @@ public class Pseudocode {
             return name;
         }
 
-        public int getTargetInstructionIndex() {
+        public Integer getTargetInstructionIndex() {
             return targetInstructionIndex;
         }
 
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/ReadValueInstruction.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/ReadValueInstruction.java
index b8847d46211..fe4f7671536 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/ReadValueInstruction.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/ReadValueInstruction.java
@@ -1,15 +1,15 @@
 package org.jetbrains.jet.lang.cfg.pseudocode;
 
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.jet.lang.psi.JetExpression;
+import org.jetbrains.jet.lang.psi.JetElement;
 
 /**
 * @author abreslav
 */
 public class ReadValueInstruction extends InstructionWithNext {
 
-    public ReadValueInstruction(@NotNull JetExpression expression) {
-        super(expression);
+    public ReadValueInstruction(@NotNull JetElement element) {
+        super(element);
     }
 
     @Override
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/Errors.java b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/Errors.java
index 6faa4c683b7..733e89b9215 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/Errors.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/Errors.java
@@ -263,7 +263,22 @@ public interface Errors {
     ParameterizedDiagnosticFactory1<CallableDescriptor> TOO_MANY_ARGUMENTS = ParameterizedDiagnosticFactory1.create(ERROR, "Too many arguments for {0}");
     ParameterizedDiagnosticFactory1<String> ERROR_COMPILE_TIME_VALUE = ParameterizedDiagnosticFactory1.create(ERROR, "{0}");
 
-    SimpleDiagnosticFactory ELSE_MISPLACED_IN_WHEN = SimpleDiagnosticFactory.create(ERROR, "'else' entry must be the last one in a when-expression");
+    SimpleDiagnosticFactoryWithPsiElement<JetWhenEntry> ELSE_MISPLACED_IN_WHEN = new SimpleDiagnosticFactoryWithPsiElement<JetWhenEntry>(ERROR, "'else' entry must be the last one in a when-expression") {
+        @NotNull
+        @Override
+        public TextRange getTextRange(@NotNull JetWhenEntry entry) {
+            PsiElement elseKeywordElement = entry.getElseKeywordElement();
+            assert elseKeywordElement != null;
+            return elseKeywordElement.getTextRange();
+        }
+    };
+    SimpleDiagnosticFactoryWithPsiElement<JetWhenExpression> NO_ELSE_IN_WHEN = new SimpleDiagnosticFactoryWithPsiElement<JetWhenExpression>(ERROR, "'when' expression must contain 'else' branch") {
+        @NotNull
+        @Override
+        public TextRange getTextRange(@NotNull JetWhenExpression element) {
+            return element.getWhenKeywordElement().getTextRange();
+        }
+    };
     SimpleDiagnosticFactory CYCLIC_INHERITANCE_HIERARCHY = SimpleDiagnosticFactory.create(ERROR, "There's a cycle in the inheritance hierarchy for this type");
 
     SimpleDiagnosticFactory MANY_CLASSES_IN_SUPERTYPE_LIST = SimpleDiagnosticFactory.create(ERROR, "Only one class may appear in a supertype list");
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/SimpleDiagnosticFactoryWithPsiElement.java b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/SimpleDiagnosticFactoryWithPsiElement.java
index a0da054399a..7600980fb3d 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/SimpleDiagnosticFactoryWithPsiElement.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/SimpleDiagnosticFactoryWithPsiElement.java
@@ -1,6 +1,7 @@
 package org.jetbrains.jet.lang.diagnostics;
 
 import com.intellij.lang.ASTNode;
+import com.intellij.openapi.util.TextRange;
 import com.intellij.psi.PsiElement;
 import org.jetbrains.annotations.NotNull;
 
@@ -15,19 +16,28 @@ public abstract class SimpleDiagnosticFactoryWithPsiElement<T extends PsiElement
         super(severity);
         this.message = message;
     }
+    
+    private Diagnostic on(@NotNull T elementToBlame, @NotNull TextRange textRange) {
+        return new DiagnosticWithPsiElementImpl<T>(this, severity, message, elementToBlame, textRange);
+    }
 
     @NotNull
     public Diagnostic on(@NotNull T elementToBlame, @NotNull ASTNode nodeToMark) {
-        return new DiagnosticWithPsiElementImpl<T>(this, severity, message, elementToBlame, nodeToMark.getTextRange());
+        return on(elementToBlame, nodeToMark.getTextRange());
     }
 
     @NotNull
     public Diagnostic on(@NotNull T elementToBlame, @NotNull PsiElement elementToMark) {
-        return new DiagnosticWithPsiElementImpl<T>(this, severity, message, elementToBlame, elementToMark.getTextRange());
+        return on(elementToBlame, elementToMark.getTextRange());
     }
 
     @NotNull
     public Diagnostic on(@NotNull T element) {
-        return on(element, element.getNode());
+        return on(element, getTextRange(element));
+    }
+    
+    @NotNull
+    public TextRange getTextRange(@NotNull T element) {
+        return element.getTextRange();
     }
 }
\ No newline at end of file
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java
index 7336820ded1..eb0f28d43a9 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java
@@ -148,4 +148,23 @@ public class JetPsiUtil {
     private static String makeFQName(String prefix, JetClassOrObject jetClass) {
         return ((prefix == null || prefix.length() == 0) ? "" : prefix + ".") + jetClass.getName();
     }
+
+    public static boolean isIrrefutable(JetWhenEntry entry) {
+        if (entry.isElse()) return true;
+        for (JetWhenCondition condition : entry.getConditions()) {
+            if (condition instanceof JetWhenConditionIsPattern) {
+                JetPattern pattern = ((JetWhenConditionIsPattern) condition).getPattern();
+                if (pattern instanceof JetWildcardPattern) {
+                    return true;
+                }
+                if (pattern instanceof JetBindingPattern) {
+                    JetBindingPattern bindingPattern = (JetBindingPattern) pattern;
+                    if (bindingPattern.getVariableDeclaration().getPropertyTypeRef() == null && bindingPattern.getCondition() == null) {
+                        return true;
+                    }
+                }
+            }
+        }
+        return false;
+    }
 }
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetWhenEntry.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetWhenEntry.java
index d4adc5210a1..d374782df1b 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetWhenEntry.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetWhenEntry.java
@@ -1,6 +1,7 @@
 package org.jetbrains.jet.lang.psi;
 
 import com.intellij.lang.ASTNode;
+import com.intellij.psi.PsiElement;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lexer.JetTokens;
@@ -14,7 +15,12 @@ public class JetWhenEntry extends JetElement {
     }
 
     public boolean isElse() {
-        return findChildByType(JetTokens.ELSE_KEYWORD) != null;
+        return getElseKeywordElement() != null;
+    }
+
+    @Nullable
+    public PsiElement getElseKeywordElement() {
+        return findChildByType(JetTokens.ELSE_KEYWORD);
     }
 
     @Nullable
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetWhenExpression.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetWhenExpression.java
index bbec3d4075c..36578540051 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetWhenExpression.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetWhenExpression.java
@@ -1,9 +1,11 @@
 package org.jetbrains.jet.lang.psi;
 
 import com.intellij.lang.ASTNode;
+import com.intellij.psi.PsiElement;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.JetNodeTypes;
+import org.jetbrains.jet.lexer.JetTokens;
 
 import java.util.List;
 
@@ -34,4 +36,9 @@ public class JetWhenExpression extends JetExpression {
     public <R, D> R accept(@NotNull JetVisitor<R, D> visitor, D data) {
         return visitor.visitWhenExpression(this, data);
     }
+
+    @NotNull
+    public PsiElement getWhenKeywordElement() {
+        return findChildByType(JetTokens.WHEN_KEYWORD);
+    }
 }
diff --git a/compiler/testData/codegen/patternMatching/exceptionOnNoMatch.jet b/compiler/testData/codegen/patternMatching/exceptionOnNoMatch.jet
index f5e668b9faf..2c98ded9809 100644
--- a/compiler/testData/codegen/patternMatching/exceptionOnNoMatch.jet
+++ b/compiler/testData/codegen/patternMatching/exceptionOnNoMatch.jet
@@ -1,3 +1,4 @@
 fun isZero(x: Int) = when(x) {
   0 -> true
+  else -> throw Exception()
 }
diff --git a/compiler/testData/diagnostics/tests/Super.jet b/compiler/testData/diagnostics/tests/Super.jet
index 1f41daa88ce..fd52c4c0b58 100644
--- a/compiler/testData/diagnostics/tests/Super.jet
+++ b/compiler/testData/diagnostics/tests/Super.jet
@@ -6,7 +6,7 @@ fun notAnExpression() {
     any(<!SUPER_IS_NOT_AN_EXPRESSION!>super<!>) // not an expression
     if (<!SUPER_IS_NOT_AN_EXPRESSION!>super<!>) {} else {} // not an expression
     val <!UNUSED_VARIABLE!>x<!> = <!SUPER_IS_NOT_AN_EXPRESSION!>super<!> // not an expression
-    when (1) {
+    <!NO_ELSE_IN_WHEN!>when<!> (1) {
         <!SUPER_IS_NOT_AN_EXPRESSION!>super<!> -> 1 // not an expression
     }
 
@@ -86,4 +86,4 @@ class A1 {
     fun test() {
         <!SUPER_IS_NOT_AN_EXPRESSION!>super<!>.equals(null)
     }
-}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/Unresolved.jet b/compiler/testData/diagnostics/tests/Unresolved.jet
index 0ec39c5fcbe..617fa8a3064 100644
--- a/compiler/testData/diagnostics/tests/Unresolved.jet
+++ b/compiler/testData/diagnostics/tests/Unresolved.jet
@@ -15,12 +15,11 @@ fun testUnresolved() {
     foo1(<!UNRESOLVED_REFERENCE!>i<!>)
     s.<!UNRESOLVED_REFERENCE!>foo<!>()
 
-    when(<!UNRESOLVED_REFERENCE!>a<!>) {
+    <!NO_ELSE_IN_WHEN!>when<!>(<!UNRESOLVED_REFERENCE!>a<!>) {
         is Int -> <!UNRESOLVED_REFERENCE!>a<!>
         is String -> <!UNRESOLVED_REFERENCE!>a<!>
     }
 
-    //TODO
     for (j in <!UNRESOLVED_REFERENCE!>collection<!>) {
        var i: Int = j
        i += 1
diff --git a/compiler/testData/diagnostics/tests/When.jet b/compiler/testData/diagnostics/tests/When.jet
index 0943aa7cdb6..e5a446c6077 100644
--- a/compiler/testData/diagnostics/tests/When.jet
+++ b/compiler/testData/diagnostics/tests/When.jet
@@ -4,7 +4,6 @@ fun foo() : Int {
     val s = ""
     val x = 1
     when (x) {
-      is * -> 1
       is <!INCOMPATIBLE_TYPES!>String<!> -> 1
       !is Int -> 1
       is Any? -> 1
@@ -16,7 +15,7 @@ fun foo() : Int {
       // Commented for KT-621 .<!!UNRESOLVED_REFERENCE!>a<!!> => 1
       // Commented for KT-621 .equals(1).<!!UNRESOLVED_REFERENCE!>a<!!> => 1
       // Commented for KT-621 <!UNNECESSARY_SAFE_CALL!!>?.<!!>equals(1) => 1
-      else -> 1
+      is * -> 1
     }
 
     // Commented for KT-621
@@ -34,7 +33,7 @@ fun test() {
   val x = 1;
   val s = "";
 
-  when (x) {
+  <!NO_ELSE_IN_WHEN!>when<!> (x) {
     <!INCOMPATIBLE_TYPES!>s<!> -> 1
     is <!INCOMPATIBLE_TYPES!>""<!> -> 1
     x -> 1
@@ -44,7 +43,7 @@ fun test() {
 
   val z = #(1, 1)
 
-  when (z) {
+  <!NO_ELSE_IN_WHEN!>when<!> (z) {
     is #(*, *) -> 1
     is #(*, 1) -> 1
     is #(1, 1) -> 1
@@ -55,8 +54,8 @@ fun test() {
   }
 
   when (z) {
-    <!ELSE_MISPLACED_IN_WHEN!>else -> 1<!>
-    #(1, 1) -> 2
+    <!ELSE_MISPLACED_IN_WHEN!>else<!> -> 1
+    <!UNREACHABLE_CODE!>#(1, 1) -> 2<!>
   }
 
   when (z) {
@@ -64,4 +63,4 @@ fun test() {
   }
 }
 
-val #(Int, Int).boo : #(Int, Int, Int) = #(1, 1, 1)
+val #(Int, Int).boo : #(Int, Int, Int) = #(1, 1, 1)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/kt786.jet b/compiler/testData/diagnostics/tests/controlStructures/kt786.jet
index e82c47aa5fc..102b7dbc3cc 100644
--- a/compiler/testData/diagnostics/tests/controlStructures/kt786.jet
+++ b/compiler/testData/diagnostics/tests/controlStructures/kt786.jet
@@ -6,19 +6,19 @@ fun foo() : Int {
     var z = 0
     when(d) {
         is 5, is 3 -> <!NO_RETURN_IN_FUNCTION_WITH_BLOCK_BODY, UNUSED_CHANGED_VALUE!>z++<!>
-        <!ELSE_MISPLACED_IN_WHEN!>else -> { <!NO_RETURN_IN_FUNCTION_WITH_BLOCK_BODY!>z = <!UNUSED_VALUE!>-1000<!><!> }<!>
-        return z -> <!UNREACHABLE_CODE!>34<!>
+        <!ELSE_MISPLACED_IN_WHEN!>else<!> -> { <!NO_RETURN_IN_FUNCTION_WITH_BLOCK_BODY!>z = <!UNUSED_VALUE!>-1000<!><!> }
+        <!UNREACHABLE_CODE!>return z -> 34<!>
     }
 }
 
 //test unreachable code
 fun fff(): Int {
     var d = 3
-    when(d) {
+    <!NO_ELSE_IN_WHEN!>when<!>(d) {
         is 4 -> 21
         return 2 -> <!UNREACHABLE_CODE!>return 47<!>
-        <!UNREACHABLE_CODE!>bar()<!> -> <!UNREACHABLE_CODE!>45<!>
-        <!UNREACHABLE_CODE!>444<!> -> <!UNREACHABLE_CODE!>true<!>
+        <!UNREACHABLE_CODE!>bar() -> 45<!>
+        <!UNREACHABLE_CODE!>444 -> true<!>
     }
     return 34
 }
diff --git a/compiler/testData/diagnostics/tests/controlStructures/when.kt234.kt973.jet b/compiler/testData/diagnostics/tests/controlStructures/when.kt234.kt973.jet
new file mode 100644
index 00000000000..f74625cc30a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/when.kt234.kt973.jet
@@ -0,0 +1,54 @@
+//KT-234 Force when() expressions to have an 'else' branch
+//KT-973 Unreachable code
+
+package kt234_kt973
+
+
+fun test(t : #(Int, Int)) : Int {
+    <!NO_ELSE_IN_WHEN!>when<!> (t) {
+        is #(10, 10) -> return 1
+    }
+    return 0 // unreachable code
+}
+
+fun test1(t : #(Int, Int)) : Int {
+    when (t) {
+        is #(10, 10) -> return 1
+        else -> return 2
+    }
+    <!UNREACHABLE_CODE!>return 0<!> // unreachable code
+}
+
+//more tests
+fun t1(x: Int) = when(x) {
+    is * -> 1
+}
+
+fun t2(x: Int) = when(x) {
+    is val a -> 1
+}
+
+fun t3(x: Int) = when (x) {
+    is * -> 1
+    <!UNREACHABLE_CODE!>2 -> 2<!>
+}
+
+fun t4(x: Int) = when (x) {
+    is val a -> 1
+    <!UNREACHABLE_CODE!>2 -> 2<!>
+}
+
+fun t5(x: Int) = <!NO_ELSE_IN_WHEN!>when<!> (x) {
+    is val a : Int -> 1
+    2 -> 2
+}
+
+fun foo3(x: Int) = when(x) {
+    <!ELSE_MISPLACED_IN_WHEN!>else<!> -> 1
+    <!UNREACHABLE_CODE!>2 -> 2<!>
+}
+
+fun foo4(x: Int) = when(x) {
+    2 -> x
+    is val a -> a
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/infos/Autocasts.jet b/compiler/testData/diagnostics/tests/infos/Autocasts.jet
index a869d644ed6..3b92d238d76 100644
--- a/compiler/testData/diagnostics/tests/infos/Autocasts.jet
+++ b/compiler/testData/diagnostics/tests/infos/Autocasts.jet
@@ -153,12 +153,12 @@ fun getStringLength(obj : Any) : Char? {
 }
 
 fun toInt(i: Int?): Int = if (i != null) i else 0
-fun illegalWhenBody(a: Any): Int = when(a) {
+fun illegalWhenBody(a: Any): Int = <!NO_ELSE_IN_WHEN!>when<!>(a) {
     is Int -> a
     is String -> <!TYPE_MISMATCH!>a<!>
 }
 fun illegalWhenBlock(a: Any): Int {
-    when(a) {
+    <!NO_ELSE_IN_WHEN!>when<!>(a) {
         is Int -> return a
         is String -> return <!TYPE_MISMATCH!>a<!>
     }
@@ -223,7 +223,7 @@ fun mergeAutocasts(a: Any?) {
   if (a is Int || a is String) {
     a.<!UNRESOLVED_REFERENCE!>compareTo<!>("")
   }
-  when (a) {
+  <!NO_ELSE_IN_WHEN!>when<!> (a) {
     is String, is Any -> a.<!UNRESOLVED_REFERENCE!>compareTo<!>("")
   }
   if (a is String && a is Any) {
diff --git a/compiler/tests/org/jetbrains/jet/codegen/PatternMatchingTest.java b/compiler/tests/org/jetbrains/jet/codegen/PatternMatchingTest.java
index 4643204921f..2f1c4fd66f1 100644
--- a/compiler/tests/org/jetbrains/jet/codegen/PatternMatchingTest.java
+++ b/compiler/tests/org/jetbrains/jet/codegen/PatternMatchingTest.java
@@ -1,6 +1,5 @@
 package org.jetbrains.jet.codegen;
 
-import jet.NoPatternMatchedException;
 import jet.Tuple2;
 
 import java.lang.reflect.Method;
@@ -25,7 +24,7 @@ public class PatternMatchingTest extends CodegenTestCase {
         loadFile();
         Method foo = generateFunction();
         assertTrue((Boolean) foo.invoke(null, 0));
-        assertThrows(foo, NoPatternMatchedException.class, null, 1);
+        assertThrows(foo, Exception.class, null, 1);
     }
 
     public void testPattern() throws Exception {
diff --git a/idea/testData/checker/Unresolved.jet b/idea/testData/checker/Unresolved.jet
index b9407e489c4..95228d79b6e 100644
--- a/idea/testData/checker/Unresolved.jet
+++ b/idea/testData/checker/Unresolved.jet
@@ -18,9 +18,9 @@ fun testUnresolved() {
     when(<error>a</error>) {
         is Int -> <error>a</error>
         is String -> <error>a</error>
+        else -> <error>a</error>
     }
 
-    //TODO
     for (j in <error>collection</error>) {
        var i: Int = j
        i += 1
diff --git a/idea/testData/checker/When.jet b/idea/testData/checker/When.jet
index 2362c95f494..c4bf4638653 100644
--- a/idea/testData/checker/When.jet
+++ b/idea/testData/checker/When.jet
@@ -4,7 +4,6 @@ fun foo() : Int {
     val s = ""
     val x = 1
     when (x) {
-      is * -> 1
       is <error>String</error> -> 1
       !is Int -> 1
       is Any? -> 1
@@ -16,7 +15,7 @@ fun foo() : Int {
       // Commented for KT-621 .<!error>a</!error> -> 1
       // Commented for KT-621 .equals(1).<!error>a</!error> -> 1
       // Commented for KT-621 <!warning>?.</!warning>equals(1) -> 1
-      else -> 1
+      is * -> 1
     }
 
     // Commented for KT-621
@@ -39,6 +38,7 @@ fun test() {
     x -> 1
     is 1 -> 1
     is <error>#(1, 1)</error> -> 1
+    else -> 1
   }
 
   val z = #(1, 1)
@@ -51,11 +51,12 @@ fun test() {
     is <error>#(1, "1", *)</error> -> 1
     is boo #(1, <error>"a"</error>, *) -> 1
     is boo <error>#(1, *)</error> -> 1
+    else -> 1
   }
 
   when (z) {
-    <error>else -> 1</error>
-    #(1, 1) -> 2
+    <error>else</error> -> 1
+    <error>#(1, 1) -> 2</error>
   }
 
   when (z) {
diff --git a/idea/testData/checker/infos/Autocasts.jet b/idea/testData/checker/infos/Autocasts.jet
index fa45c29c3ad..cfacc4c3336 100644
--- a/idea/testData/checker/infos/Autocasts.jet
+++ b/idea/testData/checker/infos/Autocasts.jet
@@ -154,11 +154,13 @@ fun toInt(i: Int?): Int = if (i != null) <info descr="Automatically cast to Int"
 fun illegalWhenBody(a: Any): Int = when(a) {
     is Int -> <info descr="Automatically cast to Int">a</info>
     is String -> <error descr="[TYPE_MISMATCH] Type mismatch: inferred type is Any but Int was expected">a</error>
+    else -> 1
 }
 fun illegalWhenBlock(a: Any): Int {
     when(a) {
         is Int -> return <info descr="Automatically cast to Int">a</info>
         is String -> return <error descr="[TYPE_MISMATCH] Type mismatch: inferred type is Any but Int was expected">a</error>
+        else -> return 1
     }
 }
 fun declarations(a: Any?) {
@@ -221,7 +223,7 @@ fun mergeAutocasts(a: Any?) {
   if (a is Int || a is String) {
     a.<error descr="Unresolved reference: compareTo">compareTo</error>("")
   }
-  when (a) {
+  <error>when</error> (a) {
     is String, is Any -> a.<error descr="Unresolved reference: compareTo">compareTo</error>("")
   }
   if (a is String && a is Any) {