diff --git a/CHANGES b/CHANGES
index ce7289da..c3489d27 100644
--- a/CHANGES
+++ b/CHANGES
@@ -14,6 +14,7 @@ Version 0.2
 - :meth:`~flask.Flask.add_url_rule` can now also register a
   view function.
 - server listens on 127.0.0.1 by default now to fix issues with chrome.
+- added external URL support.
 
 Version 0.1
 -----------
diff --git a/flask.py b/flask.py
index 15891ea1..6614cba0 100644
--- a/flask.py
+++ b/flask.py
@@ -179,6 +179,7 @@ def url_for(endpoint, **values):
 
     :param endpoint: the endpoint of the URL (name of the function)
     :param values: the variable arguments of the URL rule
+    :param _external: if set to `True`, an absolute URL is generated.
     """
     ctx = _request_ctx_stack.top
     if '.' not in endpoint:
@@ -187,7 +188,8 @@ def url_for(endpoint, **values):
             endpoint = mod + '.' + endpoint
     elif endpoint.startswith('.'):
         endpoint = endpoint[1:]
-    return ctx.url_adapter.build(endpoint, values)
+    external = values.pop('_external', False)
+    return ctx.url_adapter.build(endpoint, values, force_external=external)
 
 
 def get_template_attribute(template_name, attribute):
diff --git a/tests/flask_tests.py b/tests/flask_tests.py
index 9a36a8d2..6cddbcbd 100644
--- a/tests/flask_tests.py
+++ b/tests/flask_tests.py
@@ -227,6 +227,8 @@ class BasicFunctionalityTestCase(unittest.TestCase):
             pass
         with app.test_request_context():
             assert flask.url_for('hello', name='test x') == '/hello/test%20x'
+            assert flask.url_for('hello', name='test x', _external=True) \
+                == 'http://localhost/hello/test%20x'
 
     def test_custom_converters(self):
         from werkzeug.routing import BaseConverter