To evaluate HRT action over hemostasis we treated 45 postmenopausal women, divided in: Group 1 (N= 22, hysterectomized) and Group 2 (N= 23, with uterus), at the average age of 51.6 years and average BMI of 27.1 kg/m(2), with no significant difference in the base-line, with 17beta-oestradiol, 50 mcg/day, transdermic and continuous (group 1) associated to micronized progesterone 200 mg 12 days per month (group 2). The average of 2 samples of TAP, PTT, fibrinogen and platelet number was measured monthly during 3 months. For the total sample, there was a PTT shortening along treatment, from the second evaluation on (p= 0.006). Fibrinogen in Group 2 was significantly higher than in Group 1, from the second evaluation on (p= 0.0005). Patients with BMI > 25 presented a greater TAP shortening (p= 0.040) and a smaller fibrinogen drop (p= 0.033) than patients with BMI < 25. Prothrombotic effects predominated, especially in overweight women and in those who used progesterone.