Abstract： Objective To evaluate the efficacy and safety of the administration of enoxaparin,a low molecular weight heparin (LMWH),in the prevention of post surgical deep vein thrombosis (DVT) and pulmonary embolism (PE).Methods 1 928 patients hospitalized for general surgery were randomly divided into:(① test group (n=960) to receive enoxaparin (40 mg,s.c.,12 hours before and after surgery,then once daily for 7 consecutive days); ② control group (n=968) without intervention.The incidence of DVT,PE and bleeding were recorded for statistical analysis during hospitalization and a 2 months follow-up after discharge.Results ① No significant difference was found between the two groups in age,sex,average body mass index,type of surgery,and DVT/PE risk factors (obesity,varicose veins,and history of:venous thrombosis,chronic obstructive pulmonary disease,chronic heart failure,and hormone therapy).The percentage of non-malignant/malignant tumor surgery were 36.5％/63.5％ (average operation time 2.3 hours) in control group and 35.6％/64.4％ (2.2 hours) in test group (both P＞0.05).② During the hospitalization period,59 eases (incidence =6.1 ％) of DVT and 14 cases (incidence =1.4 ％ ) of PE (among them 6 were fetal,42.8％ of all PE cases) were found in the control group,while 28 cases of DVT (2.9％) and 3 cases (0.3％) of PE (1 fetal,33.3％ of all PE cases) were found in test group.The incidence of DVT,PE (total),and PE (fetal) were significant lower in test group (P＜ 0.05 or P＜ 0.01).During the follow-up,14 more cases of DVT (1.4％) and 1 more case (0.1％ ) of PE (a fetal) were found in the control group,and 2 more DVT cases (0.2％) in test group,with the DVT incidence in test group significantly lower (P＜0.01).(③ During the enoxaparin administration,30 cases (3.1 ％) minor bleeding and 8 cases (0.8％) major bleeding were found in the control group,while 33 cases (3.4％) minor bleeding events and 9 cases (0.9％) major bleeding events were found in the test group.The results in the two groups were not significantly different in either type of bleeding events (both P＞0.05).Also no significant difference was found in the bleeding events after the ending of enoxaparin administration and during the follow-up.Conclusion Enoxaparin may reduce the incidence of DVT and PE in patients undergoing general surgery without increased risk of bleeding.