Abstract INTRODUCTION: During extrinsic coagulation pathway, a complex is developed between factor VII, calcium and tissue factor (a cell membrane lipoprotein that is exposed after cell injury). Factor VII needs calcium and vitamin K for its biologic activation. Coronary artery disease (CAD) can be induced by increased level and activity of the coagulation factors VII, VIII and IX. In postmenopausal women, estrogen decreases blood lipids and thereby decreases risk of CAD. However, the exact effects of the estrogen on the other predisposing factors of CAD are unknown. This study was conducted to evaluate the effects of oral hormone therapy regimen on fibrinogen and other coagulation factors. methods: Sixty menopausal women with history of hysterectomy were randomly allocated in 2 groups. One group was treated with conjugated estrogen 0.625 mg/day and the other group was treated with conjugated estrogen 0.625 mg/day and medroxyprogesterone 2.5 mg/day. Serum fibrinogen level and activity of coagulation factors VII, VIII and IX and blood lipids level were checked before and 3 months after treatment. results: In the group treated with estrogen alone, mean factor VII activity showed significant increase 3 months after treatment as compared to before hormone therapy (P<0.05). There were no significant changes in mean activities of coagulation factors VIII, IX and serum fibrinogen level in patients treated with estrogen or estrogen/medroxyprogesterone after treatment (P>0.05). In both groups, hormone therapy significantly decreased serum cholesterol level and LDL-C and increased HDL-C (P>0.00), but serum triglyceride level increased in the group only treated with estrogen. Discussion: Significant increase of coagulation factor VII and serum triglyceride in estrogen-treated patients is logical. This study confirms that hormone therapy with this protocol does not change mean serum fibrinogen levels and activity of coagulation factor VIII and IX. This may be a genuine finding or may be due to inadequacy of samples, given the wide normal range of coagulation factors and serum fibrinogen. Studies with more prolonged follow-up or more samples are warranted.