The study was carried out on 75 patients undergoing hip joint surgery. The efficacy of a prophylaxis of deep vein thrombosis (DVT) by acetylsalicyclic lysine (ASL) and by a low dose heparin (LDH) combined with the ASL treatment was investigated using the 125I-fibrinogen test. DVT was not significantly decreased by the ASL application (53%) compared to the controls (60%). DVT occurred significantly less under the combined administration (27%) than in the other two groups.