Abstract: A shield assembly is provided for a needle cannula of a hypodermic syringe. The shield assembly includes inner and outer shield. The inner shield includes a guard selectively movable between a proximal position which permits use of needle cannula and a distal position which safely covers the tip of the needle cannula. The outer shield is frictionally and removably positioned over the needle cannula when the inner shield is in its proximal position. Movement of the inner shield to its distal shielding position enables alignment of cooperating locking structure on the inner shield and outer shield with one another for permanently securely locking the outer shield over the needle cannula.