Abstract: A disposable device for stabilizing a vessel during venipuncture is provided. The device includes two half body portions, each half body portion having a vascular stabilizing rib thereon. A living hinge portion connects the two half body portions and permits pivotal motion whereby the stabilizing ribs may be brought closer together while maintaining a parallel relationship therebetween. A step locking mechanism also is connected between the two half body portions which permits pivotal motion about the hinge portion in one direction only. The device is placed on the body of the patient so that the vessel subject to venipuncture lies between the two stabilizing ribs. The half body portions are then pivoted about the hinge portion so that the vessel is stabilized between the stabilizing ribs. In this manner, vessels of any dimension may be stabilized.