Abstract: To investigate the incidence of anticoagulant protein deficiency in Chinese patients with deep vein thrombosis in lower limb. Methods: Molecular markers of anticoagulant proteins were assayed in 100 patients with deep venous thrombosis in lower limb(LDVT) and 100 normal controls with respect to the activity of antithrombin(AT), protein C(PC), protein S(PS) and the incidence of activated protein C resistance（APCR）. Results: Between the LDVT group and normal group， there were significant differences in the activity of AT, PC, PS and APCR (P＜0.01～0.001). Of all patients， twentyfive were found to be abnormal， including 13 PS deficiencies, 8 PC deficiencies， 5 AT deficiencies and 4 APCR deficiencies. Conclusion: In this study, the anticoagulation protein deficiencies are frequent in Chinese LDVT patients (both congenital and acquired), suggesting the etiology of thrombophilia may be different between Chinese and Western.

Key words: Venous thrombosis, Antithrombins, Protein C, Protein S, Activated protein C resistance