A safety needle system has a sheath (12) that is capable of reciprocally sliding over the exterior of a syringe to alternately cover and uncover the needle portion of the syringe. The sheath is locked over the needle by means of a locking slot (30) and coiled spring (28). A dog (34) on the needle hub engages the locking slot and is held in position in the locking slot by the coiled spring. The sheath is reciprocally slidable on the exterior of the needle of the syringe by twisting the sheath to disengage the dog from the slot and moves the dog into a guide slot to that the sheath can be moved manually to expose the needle.
