Abstract: A retractable hypodermic syringe is provided having a syringe body forming a barrel at one end and a tubular needle connector at the opposite end which surrounds a needle support passage and forms cam surfaces and locking recesses at the end portion of the needle connector. A needle support element is positionable within the needle support passage and has cam projections which are extendible through grooves defined along the needle support passage to bring the cam projections into registry with the cam surfaces. A plunger which is receivable within the syringe barrel is provided with an elongated projection that serves both as a piston support for a resilient piston carried thereby and as a needle support actuator which is movable into releasably interlocked relation with the needle support element thus enabling the plunger to impart both rotational and linear movement to the needle support element for its locking, unlocking and retracted positions relative to the syringe body.