Memcache::add Add an item to the server boolMemcache::add stringkey mixedvar intflag intexpire Memcache::add stores variable var with key only if such key doesn't exist at the server yet. Memcache::add returns &false; if such key already exist. For the rest Memcache::add behaves similarly to Memcache::set. Also you can use memcache_add function. See example below. add('var_key', 'test variable', false, 30); ?> ]]> Memcache::add returns &true; on success or &false; on failure. See also Memcache::set, Memcache::replace.