diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 7a03644..2e38ae5 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -22,6 +22,8 @@
   support to :class:`~cryptography.x509.CertificateRevocationList`.
 * Added support for :class:`~cryptography.hazmat.primitives.kdf.scrypt.Scrypt`
   when using OpenSSL 1.1.0.
+* Added support for generating a
+  :meth:`~cryptography.x509.random_serial_number`.
 
 
 1.5 - 2016-08-26
diff --git a/docs/x509/reference.rst b/docs/x509/reference.rst
index bd88b02..bee7c17 100644
--- a/docs/x509/reference.rst
+++ b/docs/x509/reference.rst
@@ -582,7 +582,6 @@
         >>> from cryptography.hazmat.primitives.asymmetric import rsa
         >>> from cryptography.x509.oid import NameOID
         >>> import datetime
-        >>> import uuid
         >>> one_day = datetime.timedelta(1, 0, 0)
         >>> private_key = rsa.generate_private_key(
         ...     public_exponent=65537,
@@ -599,7 +598,7 @@
         ... ]))
         >>> builder = builder.not_valid_before(datetime.datetime.today() - one_day)
         >>> builder = builder.not_valid_after(datetime.datetime(2018, 8, 2))
-        >>> builder = builder.serial_number(int(uuid.uuid4()))
+        >>> builder = builder.serial_number(x509.random_serial_number())
         >>> builder = builder.public_key(public_key)
         >>> builder = builder.add_extension(
         ...     x509.BasicConstraints(ca=False, path_length=None), critical=True,
@@ -637,15 +636,17 @@
     .. method:: serial_number(serial_number)
 
         Sets the certificate's serial number (an integer).  The CA's policy
-        determines how it attributes serial numbers to certificates.  The only
-        requirement is that this number uniquely identify the certificate given
-        the issuer.
+        determines how it attributes serial numbers to certificates. This
+        number must uniquely identify the certificate given the issuer.
+        `CABForum Guidelines`_ require entropy in the serial number
+        to provide protection against hash collision attacks. For more
+        information on secure random number generation, see
+        :doc:`/random-numbers`.
 
         :param serial_number: Integer number that will be used by the CA to
             identify this certificate (most notably during certificate
-            revocation checking). Users are encouraged to use a method of
-            generating 20 bytes of entropy, e.g., UUID4. For more information
-            on secure random number generation, see :doc:`/random-numbers`.
+            revocation checking). Users should consider using
+            :func:`~cryptography.x509.random_serial_number` when possible.
 
     .. method:: not_valid_before(time)
 
@@ -2542,6 +2543,17 @@
 
         Corresponds to the dotted string ``"2.5.29.24"``.
 
+Helper Functions
+~~~~~~~~~~~~~~~~
+.. currentmodule:: cryptography.x509
+
+.. function:: random_serial_number()
+
+    .. versionadded:: 1.6
+
+    Generates a random serial number suitable for use when constructing
+    certificates.
+
 Exceptions
 ~~~~~~~~~~
 .. currentmodule:: cryptography.x509
@@ -2604,3 +2616,4 @@
 
 .. _`RFC 5280 section 4.2.1.1`: https://tools.ietf.org/html/rfc5280#section-4.2.1.1
 .. _`RFC 5280 section 4.2.1.6`: https://tools.ietf.org/html/rfc5280#section-4.2.1.6
+.. _`CABForum Guidelines`: https://cabforum.org/baseline-requirements-documents/
diff --git a/src/cryptography/x509/__init__.py b/src/cryptography/x509/__init__.py
index 968d29d..feab449 100644
--- a/src/cryptography/x509/__init__.py
+++ b/src/cryptography/x509/__init__.py
@@ -11,6 +11,7 @@
     InvalidVersion, RevokedCertificate, RevokedCertificateBuilder,
     Version, load_der_x509_certificate, load_der_x509_crl, load_der_x509_csr,
     load_pem_x509_certificate, load_pem_x509_crl, load_pem_x509_csr,
+    random_serial_number,
 )
 from cryptography.x509.extensions import (
     AccessDescription, AuthorityInformationAccess,
@@ -113,6 +114,7 @@
     "load_der_x509_csr",
     "load_pem_x509_crl",
     "load_der_x509_crl",
+    "random_serial_number",
     "InvalidVersion",
     "DuplicateExtension",
     "UnsupportedExtension",
diff --git a/src/cryptography/x509/base.py b/src/cryptography/x509/base.py
index 498ccbb..ffa7191 100644
--- a/src/cryptography/x509/base.py
+++ b/src/cryptography/x509/base.py
@@ -6,6 +6,7 @@
 
 import abc
 import datetime
+import os
 from enum import Enum
 
 import six
@@ -723,3 +724,7 @@
             )
 
         return backend.create_x509_revoked_certificate(self)
+
+
+def random_serial_number():
+    return utils.int_from_bytes(os.urandom(20), "big") >> 1
diff --git a/tests/test_x509.py b/tests/test_x509.py
index dcfbe4f..468eb39 100644
--- a/tests/test_x509.py
+++ b/tests/test_x509.py
@@ -3724,3 +3724,20 @@
     def test_not_nameattribute(self):
         with pytest.raises(TypeError):
             x509.Name(["not-a-NameAttribute"])
+
+
+def test_random_serial_number(monkeypatch):
+    sample_data = os.urandom(20)
+
+    def notrandom(size):
+        assert size == len(sample_data)
+        return sample_data
+
+    monkeypatch.setattr(os, "urandom", notrandom)
+
+    serial_number = x509.random_serial_number()
+
+    assert (
+        serial_number == utils.int_from_bytes(sample_data, "big") >> 1
+    )
+    assert utils.bit_length(serial_number) < 160