diff --git a/Doc/ldap-dn.rst b/Doc/ldap-dn.rst
index 80c5b81..c6456e8 100644
--- a/Doc/ldap-dn.rst
+++ b/Doc/ldap-dn.rst
@@ -1,4 +1,4 @@
-.. % $Id: ldap-dn.rst,v 1.7 2016/07/24 15:47:46 stroeder Exp $
+.. % $Id: ldap-dn.rst,v 1.8 2016/07/24 15:52:26 stroeder Exp $
 
 
 :py:mod:`ldap.dn` LDAP Distinguished Name handling
@@ -79,6 +79,12 @@ The :mod:`ldap.dn` module defines the following functions:
 
    .. % -> list
 
+.. function:: is_dn(dn[, flags=0])
+
+   This function checks whether *dn* is a valid LDAP distinguished name by 
+   passing it to function :func:`str2dn`.
+
+   .. % -> boolean
 
 .. _ldap-dn-example: