The present invention relates to a self-blunting blood collection needle (55) in which a blunting member (26a) is deployed upon withdrawal of a blood collection tube (56a) from the tube holder (e.g., 136), to blunt the needle (22) and so safeguard the patient and the technician from inadvertent needle sticks. The blunting member (26a) is retracted to re-sharpen the needle (22) when a subsequent collection tube is inserted into the holder (136). The deployment and retraction of the blunting member (26a) is accomplished with a mechanism (142) that is responsive to the insertion and withdrawal of the blood collection tube (56a) to retract and deploy the blunting member (26a) accordingly. One feature of the present invention is that the mechanism (142) effects blunting and re-sharpening of the needle without requiring that the technician manipulate the mechanism in a manner different from that of conventional, non-blunting collection needles. Four mechanisms are disclosed: a rack and pinion mechanism (42); a cylindrical cam mechanism (142); a lever mechanism (242) and a reversing strap mechanism (342).