Abstract: A medical safety needle assembly for a hypodermic syringe, catheter or the like. The assembly includes a hollow needle carried by a hub having at least one radially outwardly extending protrusion. A generally cylindrical hollow sheath is positioned telescopically around the hub for relative sliding reciprocal movement therebetween. The sheath, which is injection molded by the collapsible core method of plastic molding, includes at least one set of interconnecting grooves in which the protrusion is guided. A plurality of projections are positioned in the grooves to hold the protrusion, and thus the sheath, in particular locations relative to the hub and needle. First the needle is covered by the sheath to protect the needle prior to use; then the sheath is retracted to expose the needle for hypodermic use; and lastly, the sheath is moved to shield the needle to an even greater extent than it was prior to use to protect personnel from accidental needle sticks.