Because of the belief that post-operative deep vein thrombosis (DVT) is rare in Asian patients, thromboprophylaxis is not usually prescribed for surgical patients. This study reports an open multi-centre controlled study of the use of a low molecular weight heparin, nadroparin calcium (Fraxoparine Sanofi France), as opposed to no prophylaxis in 100 patients undergoing uncemented total hip replacement. The patients had bilateral venography performed preoperatively and 10 days after operation. Eight patients (16%) developed DVT in the control group of 50 patients and 1 (2%) in the treatment group, also of 50 patients. Pulmonary embolus occurred in 1 patient in the treatment group and in 3 in the control group. Intraoperative and postoperative blood loss did not differ significantly between the two groups. Our study suggests that the incidence of DVT in Asian patients, though somewhat less than in their Western counterparts, is still considerable. It confirms the safety and efficacy of nadroparin calcium in preventing post-operative DVT in patients undergoing elective total hip replacement.