UnknownNameAttribute is not needed now
diff --git a/docs/x509.rst b/docs/x509.rst
index 5ad6997..9406bd8 100644
--- a/docs/x509.rst
+++ b/docs/x509.rst
@@ -261,12 +261,6 @@
Returns the raw version that was parsed from the certificate.
-.. class:: UnknownNameAttribute
-
- This is raised when an X.509 certificate has an unknown name attribute in a
- distinguished name.
-
-
.. _`public key infrastructure`: https://en.wikipedia.org/wiki/Public_key_infrastructure
.. _`TLS`: https://en.wikipedia.org/wiki/Transport_Layer_Security
diff --git a/src/cryptography/x509.py b/src/cryptography/x509.py
index a1f8c5b..1b8d635 100644
--- a/src/cryptography/x509.py
+++ b/src/cryptography/x509.py
@@ -50,10 +50,6 @@
self.parsed_version = parsed_version
-class UnknownNameAttribute(Exception):
- pass
-
-
class NameAttribute(object):
def __init__(self, oid, value):
if not isinstance(oid, ObjectIdentifier):