Abstract: An improved syringe plunger rod for a retracting needle syringe is illustrated having a plunger rod with inner and outer members and a retaining ring. The retaining ring restricts movement between the inner and outer members until the ring makes contact with the proximal end of the retracting needle syringe and further distal force is applied to the inner member. Once disengaged, the inner member moves relative to the outer member to activate the retractable needle syringe. One advantage of the improved plunger rod is that it reduces the probability of premature activation of the retractable needle syringe. In addition, the improved plunger rod assists in the prevention of re-use of the syringe.