diff -r ed011b0d7daf Lib/test/test_xmlrpc.py
--- a/Lib/test/test_xmlrpc.py	Sun Sep 22 16:18:19 2013 -0700
+++ b/Lib/test/test_xmlrpc.py	Mon Sep 23 14:25:03 2013 +0800
@@ -380,6 +380,9 @@
             if name == 'div':
                 return 'This is the div function'
 
+    def sophisticated_function(x, y, z=1, *args, **kwargs):
+        pass
+
     def my_function():
         '''This is my function'''
         return True
@@ -411,6 +414,7 @@
         serv.register_function(pow)
         serv.register_function(lambda x,y: x+y, 'add')
         serv.register_function(my_function)
+        serv.register_function(sophisticated_function)
         serv.register_instance(TestInstanceClass())
         evt.set()
 
@@ -590,8 +594,9 @@
 
     def test_introspection1(self):
         expected_methods = set(['pow', 'div', 'my_function', 'add',
-                                'system.listMethods', 'system.methodHelp',
-                                'system.methodSignature', 'system.multicall'])
+                                'sophisticated_function', 'system.listMethods',
+                                'system.methodHelp', 'system.methodSignature',
+                                'system.multicall'])
         try:
             p = xmlrpclib.ServerProxy(URL)
             meth = p.system.listMethods()
@@ -630,12 +635,21 @@
                 self.fail("%s\n%s" % (e, getattr(e, "headers", "")))
 
     def test_introspection4(self):
-        # the SimpleXMLRPCServer doesn't support signatures, but
-        # at least check that we can try making the call
         try:
             p = xmlrpclib.ServerProxy(URL)
-            divsig = p.system.methodSignature('div')
-            self.assertEqual(divsig, 'signatures not supported')
+            sophissig = p.system.methodSignature('sophisticated_function')
+            self.assertEqual(sophissig, '(x, y, z=1, *args, **kwargs)')
+        except (xmlrpclib.ProtocolError, OSError) as e:
+            # ignore failures due to non-blocking socket 'unavailable' errors
+            if not is_unavailable_exception(e):
+                # protocol error; provide additional information in test output
+                self.fail("%s\n%s" % (e, getattr(e, "headers", "")))
+
+    def test_introspection5(self):
+        try:
+            p = xmlrpclib.ServerProxy(URL)
+            self.assertRaises(xmlrpclib.Fault, p.system.methodSignature,
+                'bogus_function')
         except (xmlrpclib.ProtocolError, OSError) as e:
             # ignore failures due to non-blocking socket 'unavailable' errors
             if not is_unavailable_exception(e):
diff -r ed011b0d7daf Lib/xmlrpc/server.py
--- a/Lib/xmlrpc/server.py	Sun Sep 22 16:18:19 2013 -0700
+++ b/Lib/xmlrpc/server.py	Mon Sep 23 14:25:03 2013 +0800
@@ -290,17 +290,16 @@
         return sorted(methods)
 
     def system_methodSignature(self, method_name):
-        """system.methodSignature('add') => [double, int, int]
+        """system.methodSignature('add') => '(x, y)'
 
         Returns a list describing the signature of the method. In the
-        above example, the add method takes two integers as arguments
-        and returns a double result.
+        above example, the add method takes two variables as arguments."""
 
-        This server does NOT support system.methodSignature."""
-
-        # See http://xmlrpc.usefulinc.com/doc/sysmethodsig.html
-
-        return 'signatures not supported'
+        try:
+            func = self.funcs[method_name]
+            return str(inspect.signature(func))
+        except KeyError:
+            raise Exception('method "%s" can not be found' % method_name)
 
     def system_methodHelp(self, method_name):
         """system.methodHelp('add') => "Adds two integers together"