38 women with pelvic endometriosis diagnosed by laparotomy or laparoscopy were enrolled in a double-blind study utilizing danazol. Danazol was administered for 6 months in four doses schedules: 600, 400, 200, and 100 mg/day. At the completion of 6 months of therapy, repeat laparoscopy was performed and 71% of the women were found to have improvement of pelvic endometriosis. Minimal and moderate pelvic endometriosis appeared to respond well to doses of danazol of less than 400 mg/day, whereas severe endometriosis appeared to be best treated with danazol doses of greater than 400 mg/day. Symptomatic relief of pain, dysmenorrhea, and dyspareunia occurred in 89% of the women. The over-all pregnancy rate in women attempting conception was 28% (8 of 28). 51% of the women had recurrence of symptoms within 1 year of discontinuation of danazol.