PIP: Data from the author's previous studies regarding changes which occur in coagulation and fibrinolytic levels in the blood of women using oral contraceptives have been compared with ABO blook groups in 307 women. Although a tendency toward hypercogulability in group A was noted, it was not statistically significant. Patients had been treated with 4 different dosage combinations of estrogen and progestins over periods varying from 3 months to 24 months. The steroid therapy had increased the levels of activity of some of the coagulation and fibrinolytic factors regardless of progestin component dosage. No differences among blood groups was shown.