<?php $a1 = array("a"=>"red", "b"=>"green", "c"=>"blue", "d"=>"yellow"); $a2 = array("e"=>"red", "f"=>"green", "g"=>"blue"); $result = array_intersect($a1, $a2); print_r($result); //Array ( [a] => red [b] => green [c] => blue )