Patients with fractures of the neck of the femur have an extremely high incidence of venous thrombosis and pulmonary emboli, if not receiving prevention therapy with drugs. From a prospective, randomized multicenter trial comparing the effectiveness of 2 methods for the prevention of postoperative fatal pulmonary emboli, patients operated on for a fracture of the neck of the femur were analyzed. Patients having had heparin-DHE prevention (172) and 157 having had dextran prevention were compared with 150 patients in the control group and 165 patients who were given phenindione for anticoagulation orally. The data from the latter 2 groups stem from a study done in 1959 by Sevitt and Gallagher which for the 1st time established the value of oral anticoagulation for reducing pulmonary emboli. All 3 prophylactic methods reduce the incidence of pulmonary emboli to the same degree. The mortality associated with pulmonary emboli was 2% in the phenindione group, 2.3% in the heparin-DHE group and 3.8% in the dextran group, in contrast with 10% in the control group. Total mortality was lowered significantly in all 3 groups as compared with the control group. Fatal pulmonary emboli were found only when prophylaxis was stopped or was incomplete and were not found when prophylactic regimen was done properly. In 1980, the hospital stay was .apprx. 1 wk shorter than in 1959.