diff --git a/docs/hazmat/primitives/constant-time.rst b/docs/hazmat/primitives/constant-time.rst
new file mode 100644
index 0000000..2e8e26d
--- /dev/null
+++ b/docs/hazmat/primitives/constant-time.rst
@@ -0,0 +1,24 @@
+.. hazmat::
+
+Constant time functions
+=======================
+
+.. currentmodule:: cryptography.hazmat.primitives.constant_time
+
+In order for cryptographic operations to not leak information through timing
+side channels, constant time operations need to be made available.
+
+.. function:: bytes_eq(a, b)
+
+    Compare ``a`` and ``b`` to one another in constant time.
+
+    .. doctest::
+
+        >>> from cryptography.hazmat.primitives import constant_time
+        >>> constant_time.bytes_eq(b"foo", b"foo")
+        True
+        >>> constant_time.bytes_eq(b"foo", b"bar")
+        False
+
+    :param a: ``bytes``.
+    :param b: ``bytes``.
diff --git a/docs/hazmat/primitives/index.rst b/docs/hazmat/primitives/index.rst
index 614c414..b115fdb 100644
--- a/docs/hazmat/primitives/index.rst
+++ b/docs/hazmat/primitives/index.rst
@@ -10,4 +10,5 @@
     hmac
     symmetric-encryption
     padding
+    constant-time
     interfaces