The safety of fondaparinux 2.5 mg has been evaluated in 3,595 patients undergoing major orthopaedic surgery of the lower limbs treated up to 9 days, in 327 patients undergoing hip fracture surgery treated for 3 weeks following an initial prophylaxis of 1 week, 1,407 patients undergoing abdominal surgery treated up to 9 days, and in 425 medical patients who are at risk for thromboembolic complications treated up to 14 days.