Abstract: A reusable arrangement to protect against accidental contact with the sharp surfaces of needles and other invasive medical instruments. In one embodiment, the invention comprises a collar that engages a sharp surgical instrument in advance of its sharp end. Attached to the collar by means of a hinge is a slotted longitudinal member, which swings over the sharp end of the instrument, thereby engaging either the collar or the portion of the instrument just in front of the collar and also retaining the instrument behind a keeper shelf. The keeper shelf may be engaged with the opposite side of the longitudinal member to lock this member over the sharp instrument. The longitudinal member may also be equipped with wing members to facilitate movement of the sharp instrument around the keeper shelf. In another embodiment, the locking mechanism comprises a set of flanges depending from the longitudinal member that are gripped by complementary catches on the collar when the device is placed into the closed position.