Abstract: An intravenous needle protection assembly has a channel-shape housing with two rails along which a needle assembly and a guard can be slid. The needle assembly carries a cannula assembly that can be slid off the needle assembly at a forward position along the housing. A rearwardly-extending, inclined resilient tab projects from the bottom of the guard and engages a locking surface at the rear edge of a recess when the guard is in the forward position. When the needle assembly is subsequently slid back to a rear position, the guard covers the tip of the needle at the forward end of the housing. A forwardly-extending resilient tab on the needle assembly then engages a locking surface at the rear of the housing to lock the needle assembly in position.