Index: src/test/org/codehaus/groovy/tools/groovydoc/testfiles/JavaClassWithMultipleInterfaces.java
===================================================================
--- src/test/org/codehaus/groovy/tools/groovydoc/testfiles/JavaClassWithMultipleInterfaces.java	(revision 0)
+++ src/test/org/codehaus/groovy/tools/groovydoc/testfiles/JavaClassWithMultipleInterfaces.java	(revision 0)
@@ -0,0 +1,4 @@
+package org.codehaus.groovy.tools.groovydoc.testfiles;
+
+public class JavaClassWithMultipleInterfaces implements GroovyInterface1, JavaInterface1 {
+}
Index: src/test/org/codehaus/groovy/tools/groovydoc/testfiles/JavaInterface1.java
===================================================================
--- src/test/org/codehaus/groovy/tools/groovydoc/testfiles/JavaInterface1.java	(revision 0)
+++ src/test/org/codehaus/groovy/tools/groovydoc/testfiles/JavaInterface1.java	(revision 0)
@@ -0,0 +1,4 @@
+package org.codehaus.groovy.tools.groovydoc.testfiles;
+
+public interface JavaInterface1 {
+}
Index: src/test/org/codehaus/groovy/tools/groovydoc/testfiles/GroovyInterfaceWithMultipleInterfaces.groovy
===================================================================
--- src/test/org/codehaus/groovy/tools/groovydoc/testfiles/GroovyInterfaceWithMultipleInterfaces.groovy	(revision 0)
+++ src/test/org/codehaus/groovy/tools/groovydoc/testfiles/GroovyInterfaceWithMultipleInterfaces.groovy	(revision 0)
@@ -0,0 +1,5 @@
+package org.codehaus.groovy.tools.groovydoc.testfiles
+
+public interface GroovyInterfaceWithMultipleInterfaces extends GroovyInterface1, JavaInterface1, Runnable {
+
+}
\ No newline at end of file
Index: src/test/org/codehaus/groovy/tools/groovydoc/testfiles/GroovyClassWithMultipleInterfaces.groovy
===================================================================
--- src/test/org/codehaus/groovy/tools/groovydoc/testfiles/GroovyClassWithMultipleInterfaces.groovy	(revision 0)
+++ src/test/org/codehaus/groovy/tools/groovydoc/testfiles/GroovyClassWithMultipleInterfaces.groovy	(revision 0)
@@ -0,0 +1,4 @@
+package org.codehaus.groovy.tools.groovydoc.testfiles
+
+class GroovyClassWithMultipleInterfaces implements GroovyInterface1, JavaInterface1 {
+}
Index: src/test/org/codehaus/groovy/tools/groovydoc/testfiles/GroovyInterface1.groovy
===================================================================
--- src/test/org/codehaus/groovy/tools/groovydoc/testfiles/GroovyInterface1.groovy	(revision 0)
+++ src/test/org/codehaus/groovy/tools/groovydoc/testfiles/GroovyInterface1.groovy	(revision 0)
@@ -0,0 +1,5 @@
+package org.codehaus.groovy.tools.groovydoc.testfiles
+
+public interface GroovyInterface1 {
+
+}
\ No newline at end of file
Index: src/test/org/codehaus/groovy/tools/groovydoc/testfiles/JavaInterfaceWithMultipleInterfaces.java
===================================================================
--- src/test/org/codehaus/groovy/tools/groovydoc/testfiles/JavaInterfaceWithMultipleInterfaces.java	(revision 0)
+++ src/test/org/codehaus/groovy/tools/groovydoc/testfiles/JavaInterfaceWithMultipleInterfaces.java	(revision 0)
@@ -0,0 +1,4 @@
+package org.codehaus.groovy.tools.groovydoc.testfiles;
+
+public interface JavaInterfaceWithMultipleInterfaces extends GroovyInterface1, JavaInterface1, Runnable {
+}
Index: src/test/org/codehaus/groovy/tools/groovydoc/GroovyDocToolTest.java
===================================================================
--- src/test/org/codehaus/groovy/tools/groovydoc/GroovyDocToolTest.java	(revision 21075)
+++ src/test/org/codehaus/groovy/tools/groovydoc/GroovyDocToolTest.java	(working copy)
@@ -176,9 +176,7 @@
         xmlTool.renderToOutput(output, MOCK_DIR);
 
         String domBuilderDoc = output.getText(MOCK_DIR + "/groovy/xml/DOMBuilder.html");
-        // TODO reinstate
-//        assertTrue(domBuilderDoc.indexOf("<extends>BuilderSupport</extends>") > 0);
-        assertTrue(domBuilderDoc.indexOf("<extends>null</extends>") > 0);
+        assertTrue(domBuilderDoc.indexOf("<extends>BuilderSupport</extends>") > 0);
     }
 
     public void testExtendsClauseWithSuperClassInTree() throws Exception {
@@ -192,6 +190,44 @@
         assertTrue(domBuilderDoc.indexOf("<extends>BuilderSupport</extends>") > 0);
     }
 
+    public void testInterfaceExtendsClauseWithMultipleInterfaces() throws Exception {
+        List<String> srcList = new ArrayList<String>();
+        srcList.add("org/codehaus/groovy/tools/groovydoc/testfiles/GroovyInterfaceWithMultipleInterfaces.groovy");
+        srcList.add("org/codehaus/groovy/tools/groovydoc/testfiles/JavaInterfaceWithMultipleInterfaces.java");
+        srcList.add("org/codehaus/groovy/tools/groovydoc/testfiles/GroovyInterface1.groovy");
+        srcList.add("org/codehaus/groovy/tools/groovydoc/testfiles/JavaInterface1.java");
+        xmlToolForTests.add(srcList);
+        MockOutputTool output = new MockOutputTool();
+        xmlToolForTests.renderToOutput(output, MOCK_DIR);
+
+        String groovyClassDoc = output.getText(MOCK_DIR + "/org/codehaus/groovy/tools/groovydoc/testfiles/GroovyInterfaceWithMultipleInterfaces.html");
+        assertTrue(groovyClassDoc.indexOf("<interface>JavaInterface1</interface>") > 0);
+        assertTrue(groovyClassDoc.indexOf("<interface>GroovyInterface1</interface>") > 0);
+
+        String javaClassDoc = output.getText(MOCK_DIR + "/org/codehaus/groovy/tools/groovydoc/testfiles/JavaInterfaceWithMultipleInterfaces.html");
+        assertTrue(javaClassDoc.indexOf("<interface>JavaInterface1</interface>") > 0);
+        assertTrue(javaClassDoc.indexOf("<interface>GroovyInterface1</interface>") > 0);
+    }
+
+    public void testImplementsClauseWithMultipleInterfaces() throws Exception {
+        List<String> srcList = new ArrayList<String>();
+        srcList.add("org/codehaus/groovy/tools/groovydoc/testfiles/GroovyClassWithMultipleInterfaces.groovy");
+        srcList.add("org/codehaus/groovy/tools/groovydoc/testfiles/JavaClassWithMultipleInterfaces.java");
+        srcList.add("org/codehaus/groovy/tools/groovydoc/testfiles/GroovyInterface1.groovy");
+        srcList.add("org/codehaus/groovy/tools/groovydoc/testfiles/JavaInterface1.java");
+        xmlToolForTests.add(srcList);
+        MockOutputTool output = new MockOutputTool();
+        xmlToolForTests.renderToOutput(output, MOCK_DIR);
+
+        String groovyClassDoc = output.getText(MOCK_DIR + "/org/codehaus/groovy/tools/groovydoc/testfiles/GroovyClassWithMultipleInterfaces.html");
+        assertTrue(groovyClassDoc.indexOf("<interface>JavaInterface1</interface>") > 0);
+        assertTrue(groovyClassDoc.indexOf("<interface>GroovyInterface1</interface>") > 0);
+
+        String javaClassDoc = output.getText(MOCK_DIR + "/org/codehaus/groovy/tools/groovydoc/testfiles/JavaClassWithMultipleInterfaces.html");
+        assertTrue(javaClassDoc.indexOf("<interface>JavaInterface1</interface>") > 0);
+        assertTrue(javaClassDoc.indexOf("<interface>GroovyInterface1</interface>") > 0);
+    }
+
     public void testDefaultPackage() throws Exception {
         List<String> srcList = new ArrayList<String>();
         srcList.add("UberTestCaseBugs.java");
@@ -199,9 +235,7 @@
         MockOutputTool output = new MockOutputTool();
         xmlToolForTests.renderToOutput(output, MOCK_DIR);
         String domBuilderDoc = output.getText(MOCK_DIR + "/DefaultPackage/UberTestCaseBugs.html");
-        // TODO reinstate
-//        assertTrue(domBuilderDoc.indexOf("<extends>TestCase</extends>") > 0);
-        assertTrue(domBuilderDoc.indexOf("<extends>null</extends>") > 0);
+        assertTrue(domBuilderDoc.indexOf("<extends>TestCase</extends>") > 0);
     }
 
     public void testStaticModifier() throws Exception {
Index: src/main/org/codehaus/groovy/tools/groovydoc/ExternalGroovyClassDoc.java
===================================================================
--- src/main/org/codehaus/groovy/tools/groovydoc/ExternalGroovyClassDoc.java	(revision 21075)
+++ src/main/org/codehaus/groovy/tools/groovydoc/ExternalGroovyClassDoc.java	(working copy)
@@ -290,7 +290,7 @@
     }
 
     public String name() {
-        return null;
+        return externalClass.getSimpleName();
     }
 
     public void setRawCommentText(String arg0) {
Index: src/main/org/codehaus/groovy/tools/groovydoc/SimpleGroovyClassDocAssembler.java
===================================================================
--- src/main/org/codehaus/groovy/tools/groovydoc/SimpleGroovyClassDocAssembler.java	(revision 21075)
+++ src/main/org/codehaus/groovy/tools/groovydoc/SimpleGroovyClassDocAssembler.java	(working copy)
@@ -167,8 +167,7 @@
     public void visitExtendsClause(GroovySourceAST t, int visit) {
         SimpleGroovyClassDoc currentClassDoc = getCurrentClassDoc();
         if (visit == OPENING_VISIT) {
-            GroovySourceAST superClassNode = t.childOfType(IDENT);
-            if (superClassNode != null) {
+            for (GroovySourceAST superClassNode : findTypeNames(t)) {
                 String superClassName = extractName(superClassNode);
                 if (currentClassDoc.isInterface()) {
                     currentClassDoc.addInterfaceName(superClassName);
@@ -182,13 +181,25 @@
     @Override
     public void visitImplementsClause(GroovySourceAST t, int visit) {
         if (visit == OPENING_VISIT) {
-            GroovySourceAST classNode = t.childOfType(IDENT);
-            if (classNode != null) {
+            for (GroovySourceAST classNode : findTypeNames(t)) {
                 getCurrentClassDoc().addInterfaceName(extractName(classNode));
             }
         }
     }
 
+    private List<GroovySourceAST> findTypeNames(GroovySourceAST t) {
+        List<GroovySourceAST> types = new ArrayList<GroovySourceAST>();
+        for (AST child = t.getFirstChild(); child != null; child = child.getNextSibling()) {
+            GroovySourceAST groovySourceAST = (GroovySourceAST) child;
+            if (groovySourceAST.getType() == IDENT) {
+                types.add(groovySourceAST);
+            }else if (groovySourceAST.getType() == TYPE) {
+                types.add(groovySourceAST.childOfType(IDENT));
+            }
+        }
+        return types;
+    }
+
     @Override
     public void visitCtorIdent(GroovySourceAST t, int visit) {
         if (visit == OPENING_VISIT && !insideEnum && !insideAnonymousInnerClass()) {
Index: src/main/org/codehaus/groovy/tools/groovydoc/gstringTemplates/classLevel/classDocStructuredData.xml
===================================================================
--- src/main/org/codehaus/groovy/tools/groovydoc/gstringTemplates/classLevel/classDocStructuredData.xml	(revision 21075)
+++ src/main/org/codehaus/groovy/tools/groovydoc/gstringTemplates/classLevel/classDocStructuredData.xml	(working copy)
@@ -1,6 +1,10 @@
 <class name="${classDoc.name()}">
   <containingPackage name="${classDoc.containingPackage().name()}">${classDoc.containingPackage().nameWithDots()}</containingPackage>
   <extends>${classDoc.superclass()?.name()}</extends>
+  <interfaces><% for (interfaceDoc in classDoc.interfaces()) { %>
+    <interface>${interfaceDoc.name()}</interface>
+<% } %>
+  </interfaces>
   <comment>${classDoc.commentText()}</comment>
   <constructors><% for (constructor in classDoc.constructors()) { %>
     <constructor modifiers="${constructor.isPublic()?'public ':''}" name="${constructor.name()}">
Index: src/main/org/codehaus/groovy/tools/groovydoc/SimpleGroovyDoc.java
===================================================================
--- src/main/org/codehaus/groovy/tools/groovydoc/SimpleGroovyDoc.java	(revision 21075)
+++ src/main/org/codehaus/groovy/tools/groovydoc/SimpleGroovyDoc.java	(working copy)
@@ -169,10 +169,10 @@
 
     // Methods from Comparable
     public int compareTo(Object that) {
-        if (that instanceof SimpleGroovyDoc) {
-            return name.compareTo(((SimpleGroovyDoc) that).name);
+        if (that instanceof GroovyDoc) {
+            return name.compareTo(((GroovyDoc) that).name());
         } else {
-            throw new ClassCastException();
+            throw new ClassCastException(String.format("Cannot compare object of type %s.", that.getClass()));
         }
     }