Forty-nine women diagnosed as having pelvic endometriosis were treated with 800 mg of danazol/day for a mean duration of 6 months. The average length of the follow-up period was 78 months. Side effects were minimal, and regular ovulatory menses returned within 25 to 90 days (average 42 days). Forty-two (85.7% of these women had associated infertility. Recurrence of symptoms was reported in 33% but in no patient were the symptoms worse than before entering the study. Of 30 patients desirous of pregnancy, 20 were potentially fertile; of these, 10 conceived within 6 months of discontinuing therapy, for a conception rate of 50%. Nine of the remaining ten patients required additional therapeutic procedures (surgery and/or danazol), and four of these conceived within 12 months. These results compare favorably with those of other investigations, since most of our patients were referred to us after being subjected to a variety of regimens, both hormonal and surgical.