509 patients who had undergone hip fracture surgery received daily open-label semuloparin injections for 7-10 days following surgery (run-in phase). Afterwards, 469 patients were randomized to receive either semuloparin injections or placebo injections for 19-23 days, to compare the safety and efficacy of extended thromboprophylaxis. Following 24 days results indicated that extended thromboprophylaxis with semuloparin was significantly more effective than the placebo in lowering the occurrence of venous thromboembolism or all-cause death. However, there were 2 bleeding events reported in the semuloparin group.