diff --git a/openssl/src/rand.rs b/openssl/src/rand.rs
index c1c49e7b..da52ef5f 100644
--- a/openssl/src/rand.rs
+++ b/openssl/src/rand.rs
@@ -1,9 +1,37 @@
+//! Utilities for secure random number generation.
+//!
+//! # Examples
+//!
+//! To generate a buffer with cryptographically strong bytes:
+//!
+//! ```
+//! use openssl::rand::rand_bytes;
+//!
+//! let mut buf = [0; 256];
+//! rand_bytes(&mut buf).unwrap();
+//! ```
 use libc::c_int;
 use ffi;
 
 use cvt;
 use error::ErrorStack;
 
+/// Fill buffer with cryptographically strong pseudo-random bytes.
+///
+/// # Examples
+///
+/// To generate a buffer with cryptographically strong bytes:
+///
+/// ```
+/// use openssl::rand::rand_bytes;
+///
+/// let mut buf = [0; 256];
+/// rand_bytes(&mut buf).unwrap();
+/// ```
+///
+/// # External OpenSSL Documentation
+///
+/// [RAND_bytes](https://www.openssl.org/docs/man1.1.0/crypto/RAND_bytes.html)
 pub fn rand_bytes(buf: &mut [u8]) -> Result<(), ErrorStack> {
     unsafe {
         ffi::init();