Micronized 17beta-estradiol (E2) was used as oral replacement therapy in 369 patients with estrogen deficiency and related menopausal symptoms. Over 95 percent of 319 patients evaluable for efficacy gained satisfactory relief of their symptoms from cyclic (on 21 days/off 7 days) E2 therapy. Approximately 77 percent required no adjustment of their initial daily dose, viz, 1 mg (5 or less hot flushes per day) or 2 mg (6 or more flushes daily). In addition, 80 percent (58/72) of the patents who did not obtain adequate control from their starting dose were successfully titrated, either upward to a maximum of 4 mg/day or downward for maintenance. Overall, a higher percentage of patients were treated successfully with 2 mg daily (209/319; 66 percent) than with 1 mg/day (22 percent). About 8 percent of the patients required 3 or 4 mg daily, while 4 percent failed to derive adequate benefit from micronized E2. Oral E2 therapy was well tolerated; hence, the attrition rate due to side effects or lack of control was only 6 percent (22/369). Moreover, all laboratory fingings were within normal limits, even in patients treated with E2 for over 12 months. Coincidental endometrial changes were found in 9 patients, all of whom had received long-term (9 months-3 years) estrogen therapy prior to entering this study. Thus, the stste of the endometrium should be determined before any estrogens are given for the monopause. It is concluded that micronized E2 is highly efficacious, well accepted, and safe for oral estrogen-replacement therapy in menopausal women.