1. 1. A systemic hemostatic agent which is consistently capable of improving visibility of the operative site, as well as reducing blood loss and the postoperative incidence of ecchymosis and/or prolonged bleeding, would constitute a valuable addition to the therapeutic armamentarium of the oral surgeon. 2. 2. A review of the clinical literature reveals that Premarin's effectiveness as a hemostatic agent remains a somewhat unsettled and controversial subject. 3. 3. A double-blind study was conducted, with controls, in order to evaluate the effectiveness of Premarin as a hemostatic agent in a variety of oral surgical procedures performed under regional anesthesia (Part I) and under general anesthesia (Part II). 4. 4. Premarin was effective in reducing blood loss in 76 per cent of the patients in Part I of the study. The mean blood loss with the placebo was 40.666 c.c., whereas it was only 23.666 c.c. with Premarin. There was a 41.69 per cent reduction in mean blood loss when the estrogen was used in this first part of the study. The optimum hemostatic effect was achieved when Premarin was administered 28.791 minutes before surgery. Premarin was just as effective in men as it was in women. However, Negro patients appeared to derive slightly more beneficial therapeutic results from Premarin than white patients. While the Negro patients had a 46.08 per cent reduction in mean blood loss, the white patients exhibited a reduction of only 21.28 per cent in mean blood loss. 5. 5. The twenty-five full-mouth extraction patients who received Premarin had a mean blood loss of 264.52 c.c., whereas the twenty-five full-mouth extraction patients who received the placebo had a mean blood loss of 308.08 c.c. There was a 14.11 per cent reduction in the mean blood loss when the estrogen was used in this second part of the study. Although Premarin was administered 15.12 minutes preoperatively, it was observed that the maximum hemostasis usually occurred 30 minutes after the surgical procedure was begun. Therefore, it is believed that the drug should be administered at least 1 2 to 3 4 hour preoperatively when it is used for full-mouth extractions, open reduction of facial fractures, and other extensive oral surgical procedures performed under general anesthesia. Sex and race were not statistically significant factors in Premarin's effect on the blood loss in this part of the study. 6. 6. It is our opinion that Part I of the study provided a more accurate appraisal of the estrogen's hemostatic effectiveness, for each patient served as his own control, receiving both the placebo and Premarin, and a relatively constant number of teeth were extracted for each of his two procedures. In Part II, however, a highly variable number of teeth were extracted in a heterogeneous group of patients (of unequal sex and race distribution), whose metabolic and periodontal conditions also showed considerable variation. 7. 7. Prolonged postextraction bleeding was not encountered in any of the Premarin-treated patients in this study. The incidence of postoperative ecchymosis was rather negligible for both the Premarin- and placebo-treated patients in both parts of the study. 8. 8. Premarin was exceedingly well tolerated and did not cause any reactions or side effects in any of the patients in either part of the study. 9. 9. In both parts of the study Premarin proved to be a safe and effective agent in reducing blood loss, as well as significantly preventing postextraction bleeding, ecchymosis, and hematoma formation.