Abstract: A safety IV catheter includes an end cap or guard and a disc-shaped lock plate having an opening through which the needle passes. One end of an actuator member passes through a second off-center opening in the lock plate and its other end passes through a flange fitted about the needle hub. In the prepared or ready position of the catheter, the guard is mounted about the distal end of the needle hub. As the needle is retracted to the activated position, the needle tip is received within the needle guard and the lost motion of the actuator member is taken up by the engagement of the needle hub and the lower end of the actuator member. This, in turn, causes the lock plate to be canted or rocked at an angle about the distal end of the needle to grip and lock the needle tip within the needle guard and to prevent further axial movement of the needle.