Disposable safety syringe

A safety syringe 10 includes a generally tubular body 14 having a needle end 18 and plunger end 22, needle 38 and retractable needle seat 30, two-way valve 36, plunger 42, stopper 62, and rear plunger seal 44. The plunger may be selectively engageable with both the stopper and the retractable needle seat. During use, the plunger may be moved to capture the stopper. The user then moves the plunger and the captured stopper toward the needle end to a displaced position corresponding to the desired volume of fluid to be withdrawn. A vacuum is created between the stopper and rear plunger seal, and helps to draw fluid into the tubular body. At the conclusion of the patient injection stroke, the plunger engages the needle seat, and the vacuum between the stopper and rear plunger seal retracts the needle safely into the tubular body. The two-way valve controls flow into and out of the body during use.