A safety syringe including a needle shield which is movable between a retracted position wherein the needle is exposed and an extended position wherein the distal needle point is protected. The needle shield is also rotatable in either direction from the releasable extended position to a locked and extended position. A collar having a plurality of protrusions and locking slots thereon is mounted on the distal end of the syringe to interact with a plurality of elongate keys which extend inwardly from the interior surface of the needle shield.