either use a hash or loop through your new array to check if entry already exists. i'm sure you've already thought of that...so what else do you want? that's the behaviour of hashes and arrays. if you want to get fancy...then use a pseudo hash, so you can access it like a hash and an array. then you can check for existing entry with hash syntax and add new entry with array syntax. look up "pseudo hash" in any good perl turorial.