 <p><code>array_unique()</code> only supports multi-dimensional arrays in PHP 5.2.9 and higher.</p> <p>Instead, you can create a hash of the array and check it for unique-ness.</p> <pre><code>$hashes = array(); foreach($array as $val) { $hashes[md5(serialize($val))] = $val; } array_unique($hashes); </code></pre>