Abstract: A retractable syringe characterized by a syringe needle which can be retracted into the barrel of the syringe and locked therein after use, to prevent accidental needle sticks or re-use of the syringe. In a preferred embodiment the syringe barrel is terminated by a tapered barrel neck which communicates with the syringe barrel interior and threadibly receives the needle hub of a cannulated syringe needle. A syringe plunger, slidably disposed in the syringe barrel, is terminated by a plunger nipple for threadibly engaging the interior of the needle hub. After the syringe plunger is operated to expel the liquid contents of the syringe barrel through the syringe needle, the plunger is rotated in the barrel to threadibly seat the plunger nipple in the needle hub. Continued rotation of the plunger in the barrel threads the attached needle hub and needle into the syringe barrel. In a preferred embodiment a pair of flexible plunger lock tabs is fitted on the plunger.