diff --git a/dlls/webservices/tests/writer.c b/dlls/webservices/tests/writer.c
index 0e67eaf7a83..446fa1dcc28 100644
--- a/dlls/webservices/tests/writer.c
+++ b/dlls/webservices/tests/writer.c
@@ -1211,6 +1211,98 @@ static void test_WsWriteXmlnsAttribute(void)
     WsFreeWriter( writer );
 }
 
+static void prepare_prefix_test( WS_XML_WRITER *writer )
+{
+    const WS_XML_STRING p = {1, (BYTE *)"p"}, localname = {1, (BYTE *)"t"}, ns = {2, (BYTE *)"ns"};
+    HRESULT hr;
+
+    hr = set_output( writer );
+    ok( hr == S_OK, "got %08x\n", hr );
+    hr = WsWriteStartElement( writer, &p, &localname, &ns, NULL );
+    ok( hr == S_OK, "got %08x\n", hr );
+    hr = WsWriteEndStartElement( writer, NULL );
+    ok( hr == S_OK, "got %08x\n", hr );
+}
+
+static void test_WsGetPrefixFromNamespace(void)
+{
+    const WS_XML_STRING p = {1, (BYTE *)"p"}, localname = {1, (BYTE *)"t"}, *prefix;
+    const WS_XML_STRING ns = {2, (BYTE *)"ns"}, ns2 = {3, (BYTE *)"ns2"};
+    WS_XML_WRITER *writer;
+    HRESULT hr;
+
+    hr = WsCreateWriter( NULL, 0, &writer, NULL ) ;
+    ok( hr == S_OK, "got %08x\n", hr );
+
+    hr = set_output( writer );
+    ok( hr == S_OK, "got %08x\n", hr );
+    hr = WsWriteStartElement( writer, &p, &localname, &ns, NULL );
+    ok( hr == S_OK, "got %08x\n", hr );
+
+    hr = WsGetPrefixFromNamespace( NULL, NULL, FALSE, NULL, NULL );
+    ok( hr == E_INVALIDARG, "got %08x\n", hr );
+
+    hr = WsGetPrefixFromNamespace( NULL, NULL, FALSE, &prefix, NULL );
+    ok( hr == E_INVALIDARG, "got %08x\n", hr );
+
+    hr = WsGetPrefixFromNamespace( writer, NULL, FALSE, &prefix, NULL );
+    ok( hr == E_INVALIDARG, "got %08x\n", hr );
+
+    /* element must be committed */
+    hr = set_output( writer );
+    ok( hr == S_OK, "got %08x\n", hr );
+    hr = WsWriteStartElement( writer, &p, &localname, &ns, NULL );
+    ok( hr == S_OK, "got %08x\n", hr );
+    hr = WsGetPrefixFromNamespace( writer, &ns, TRUE, &prefix, NULL );
+    ok( hr == WS_E_INVALID_FORMAT, "got %08x\n", hr );
+
+    /* but writer can't be positioned on end element node */
+    hr = set_output( writer );
+    ok( hr == S_OK, "got %08x\n", hr );
+    hr = WsWriteStartElement( writer, &p, &localname, &ns, NULL );
+    ok( hr == S_OK, "got %08x\n", hr );
+    hr = WsWriteEndElement( writer, NULL );
+    ok( hr == S_OK, "got %08x\n", hr );
+    hr = WsGetPrefixFromNamespace( writer, &ns, TRUE, &prefix, NULL );
+    ok( hr == WS_E_INVALID_FORMAT, "got %08x\n", hr );
+
+    /* required = TRUE */
+    prefix = NULL;
+    prepare_prefix_test( writer );
+    hr = WsGetPrefixFromNamespace( writer, &ns, TRUE, &prefix, NULL );
+    ok( hr == S_OK, "got %08x\n", hr );
+    ok( prefix != NULL, "prefix not set\n" );
+    if (prefix)
+    {
+        ok( prefix->length == 1, "got %u\n", prefix->length );
+        ok( !memcmp( prefix->bytes, "p", 1 ), "wrong prefix\n" );
+    }
+
+    prefix = (const WS_XML_STRING *)0xdeadbeef;
+    hr = WsGetPrefixFromNamespace( writer, &ns2, TRUE, &prefix, NULL );
+    ok( hr == WS_E_INVALID_FORMAT, "got %08x\n", hr );
+    ok( prefix == (const WS_XML_STRING *)0xdeadbeef, "prefix set\n" );
+
+    /* required = FALSE */
+    prefix = NULL;
+    prepare_prefix_test( writer );
+    hr = WsGetPrefixFromNamespace( writer, &ns, FALSE, &prefix, NULL );
+    ok( hr == S_OK, "got %08x\n", hr );
+    ok( prefix != NULL, "prefix not set\n" );
+    if (prefix)
+    {
+        ok( prefix->length == 1, "got %u\n", prefix->length );
+        ok( !memcmp( prefix->bytes, "p", 1 ), "wrong prefix\n" );
+    }
+
+    prefix = (const WS_XML_STRING *)0xdeadbeef;
+    hr = WsGetPrefixFromNamespace( writer, &ns2, FALSE, &prefix, NULL );
+    ok( hr == S_FALSE, "got %08x\n", hr );
+    ok( prefix == NULL, "prefix not set\n" );
+
+    WsFreeWriter( writer );
+}
+
 START_TEST(writer)
 {
     test_WsCreateWriter();
@@ -1227,4 +1319,5 @@ START_TEST(writer)
     test_WsWriteAttribute();
     test_WsWriteStartCData();
     test_WsWriteXmlnsAttribute();
+    test_WsGetPrefixFromNamespace();
 }
diff --git a/dlls/webservices/webservices.spec b/dlls/webservices/webservices.spec
index 3b0f1fc6c2d..f0a843ae3a5 100644
--- a/dlls/webservices/webservices.spec
+++ b/dlls/webservices/webservices.spec
@@ -79,7 +79,7 @@
 @ stub WsGetOperationContextProperty
 @ stub WsGetPolicyAlternativeCount
 @ stub WsGetPolicyProperty
-@ stub WsGetPrefixFromNamespace
+@ stdcall WsGetPrefixFromNamespace(ptr ptr long ptr ptr)
 @ stdcall WsGetReaderNode(ptr ptr ptr)
 @ stub WsGetReaderPosition
 @ stdcall WsGetReaderProperty(ptr long ptr long ptr)
diff --git a/dlls/webservices/writer.c b/dlls/webservices/writer.c
index f55f6440a73..14bddfbd758 100644
--- a/dlls/webservices/writer.c
+++ b/dlls/webservices/writer.c
@@ -493,6 +493,37 @@ static inline BOOL is_current_namespace( struct writer *writer, const WS_XML_STR
     return (WsXmlStringEquals( writer->current_ns, ns, NULL ) == S_OK);
 }
 
+/**************************************************************************
+ *          WsGetPrefixFromNamespace		[webservices.@]
+ */
+HRESULT WINAPI WsGetPrefixFromNamespace( WS_XML_WRITER *handle, const WS_XML_STRING *ns,
+                                         BOOL required, const WS_XML_STRING **prefix,
+                                         WS_ERROR *error )
+{
+    struct writer *writer = (struct writer *)handle;
+    WS_XML_ELEMENT_NODE *elem;
+    BOOL found = FALSE;
+
+    TRACE( "%p %s %d %p %p\n", handle, debugstr_xmlstr(ns), required, prefix, error );
+    if (error) FIXME( "ignoring error parameter\n" );
+
+    if (!writer || !ns || !prefix) return E_INVALIDARG;
+
+    elem = &writer->current->hdr;
+    if (elem->prefix && is_current_namespace( writer, ns ))
+    {
+        *prefix = elem->prefix;
+        found = TRUE;
+    }
+    if (!found)
+    {
+        if (required) return WS_E_INVALID_FORMAT;
+        *prefix = NULL;
+        return S_FALSE;
+    }
+    return S_OK;
+}
+
 static HRESULT set_current_namespace( struct writer *writer, const WS_XML_STRING *ns )
 {
     WS_XML_STRING *str;
diff --git a/include/webservices.h b/include/webservices.h
index 73b7f0a688b..cd82cb750e4 100644
--- a/include/webservices.h
+++ b/include/webservices.h
@@ -556,6 +556,8 @@ void WINAPI WsFreeWriter(WS_XML_WRITER*);
 HRESULT WINAPI WsGetErrorProperty(WS_ERROR*, WS_ERROR_PROPERTY_ID, void*, ULONG);
 HRESULT WINAPI WsGetErrorString(WS_ERROR*, ULONG, WS_STRING*);
 HRESULT WINAPI WsGetHeapProperty(WS_HEAP*, WS_HEAP_PROPERTY_ID, void*, ULONG, WS_ERROR*);
+HRESULT WINAPI WsGetPrefixFromNamespace(WS_XML_WRITER*, const WS_XML_STRING*, BOOL,
+                                        const WS_XML_STRING**, WS_ERROR*);
 HRESULT WINAPI WsGetReaderNode(WS_XML_READER*, const WS_XML_NODE**, WS_ERROR*);
 HRESULT WINAPI WsGetReaderPosition(WS_XML_READER*, WS_XML_NODE_POSITION*, WS_ERROR*);
 HRESULT WINAPI WsGetReaderProperty(WS_XML_READER*, WS_XML_READER_PROPERTY_ID, void*, ULONG, WS_ERROR*);