diff --git a/CHANGES.rst b/CHANGES.rst
index 0225840..3c71cb2 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -4,6 +4,9 @@ unreleased
 Features
 --------
 
+- Add new exception ExtraItemsError. Used to pass to the caller a list of extra
+  field detected in cstruct.
+
 - Add ``drop`` functionality to ``Sequence`` type.
 
 Bug Fixes
diff --git a/CONTRIBUTORS.txt b/CONTRIBUTORS.txt
index c3fdf73..2d2b979 100644
--- a/CONTRIBUTORS.txt
+++ b/CONTRIBUTORS.txt
@@ -126,4 +126,5 @@ Contributors
 - Nando Florestan, 2014/11/27
 - Amos Latteier, 2014/11/30
 - Jimmy Thrasibule, 2014/12/11
+- Dmitry Bogun, 2015/09/10
 - Tinne Cahy, 2015/12/22
diff --git a/colander/__init__.py b/colander/__init__.py
index d4b00ba..dae7f44 100644
--- a/colander/__init__.py
+++ b/colander/__init__.py
@@ -205,6 +205,18 @@ class Invalid(Exception):
         result of an execution of this exception's ``asdict`` method"""
         return pprint.pformat(self.asdict())
 
+
+class UnsupportedFields(Invalid):
+    """
+    Exception used when schema object detect unknown fields in the
+    cstruct during deserialize.
+    """
+
+    def __init__(self, node, items, msg=None):
+        super(UnsupportedFields, self).__init__(node, msg)
+        self.items = items
+
+
 class All(object):
     """ Composite validator which succeeds if none of its
     subvalidators raises an :class:`colander.Invalid` exception"""
@@ -667,11 +679,10 @@ class Mapping(SchemaType):
 
         if self.unknown == 'raise':
             if value:
-                raise Invalid(
-                    node,
-                    _('Unrecognized keys in mapping: "${val}"',
-                      mapping={'val':value})
-                    )
+                raise UnsupportedFields(
+                    node, value,
+                    msg=_('Unrecognized keys in mapping: "${val}"',
+                          mapping={'val': value}))
 
         elif self.unknown == 'preserve':
             result.update(value)
diff --git a/colander/tests/test_colander.py b/colander/tests/test_colander.py
index 1317747..88b90e5 100644
--- a/colander/tests/test_colander.py
+++ b/colander/tests/test_colander.py
@@ -718,10 +718,12 @@ class TestMapping(unittest.TestCase):
         self.assertEqual(result, {'a':1})
 
     def test_deserialize_unknown_raise(self):
+        import colander
         node = DummySchemaNode(None)
         node.children = [DummySchemaNode(None, name='a')]
         typ = self._makeOne(unknown='raise')
         e = invalid_exc(typ.deserialize, node, {'a':1, 'b':2})
+        self.assertTrue(isinstance(e, colander.UnsupportedFields))
         self.assertEqual(e.msg.interpolate(),
                          "Unrecognized keys in mapping: \"{'b': 2}\"")
 
diff --git a/docs/api.rst b/docs/api.rst
index 3ecc9cc..872311e 100644
--- a/docs/api.rst
+++ b/docs/api.rst
@@ -48,6 +48,15 @@ Exceptions
        from a widget as the value which should be redisplayed when an
        error is shown.
 
+  .. autoclass:: UnsupportedFields
+
+     .. attribute:: fields
+
+        The ``dict`` with all detected extra fields and their values.
+
+        Nodes that contain extra fields can be located by the position of
+        this exception in the exception tree hierarchy.
+
   .. autoclass:: UnboundDeferredError