A post-injection needle sheath for enclosing the sharpened end of a needle used with a syringe is shown with and without spring actuation. This sheath is initially in a compact and secured condition on the needle hub and has a substantial portion of the needle exposed for insertion into a patient or vial. Two embodiments employ a compression spring. Three embodiments avoid a spring per se, but have a corrugated portion and a flange portion that are manipulated by an attendant to urge the sheath forward to enclose the sharpened end of the needle. In all embodiments, the forward end includes a transverse wall in which is formed an aperture that is slightly larger than the shank of the needle. Protection to the exposed needle before use is provided by a conventionally removeable shield which is removed at time of use. After withdrawal of the needle from the patient, the sheath, with the cap or end portion, is moved forward to enclose the sharpened needle.