diff -r 9db2758c3372 src/pkg/encoding/xml/marshal.go
--- a/src/pkg/encoding/xml/marshal.go	Thu Apr 26 13:32:05 2012 -0700
+++ b/src/pkg/encoding/xml/marshal.go	Wed May 30 01:04:33 2012 +0800
@@ -273,7 +273,7 @@
 	s := parentStack{printer: p}
 	for i := range tinfo.fields {
 		finfo := &tinfo.fields[i]
-		if finfo.flags&(fAttr|fAny) != 0 {
+		if finfo.flags&(fAttr) != 0 {
 			continue
 		}
 		vf := val.FieldByIndex(finfo.idx)
diff -r 9db2758c3372 src/pkg/encoding/xml/marshal_test.go
--- a/src/pkg/encoding/xml/marshal_test.go	Thu Apr 26 13:32:05 2012 -0700
+++ b/src/pkg/encoding/xml/marshal_test.go	Wed May 30 01:04:33 2012 +0800
@@ -653,7 +653,7 @@
 	},
 	{
 		Value:       &AnyTest{Nested: "known", AnyField: AnyHolder{XML: "<unknown/>"}},
-		ExpectXML:   `<a><nested><value>known</value></nested></a>`,
+		ExpectXML:   `<a><nested><value>known</value></nested><AnyField><unknown/></AnyField></a>`,
 		MarshalOnly: true,
 	},