Efficacy of oral medroxyprogesterone acetate (MPA) was assessed in 35 women with an established diagnosis of endometriosis (33 pelvic and 2 abdominal). MPA was given in a dosage of 30 mg daily for 90 days. Results indicated improvement or remission in all cases, even though breakthrough bleeding occurred in 8. Twenty-six were treated for associated infertility. Twelve of these became pregnant following treatment. Pregnancy rate in those women whose husbands were fertile was 90%. Side effects included spotting and breakthrough bleeding. The patients usually remained amenorrheic and anovulatory while receiving MPA. Posttreatment resumption of ovulation was prompt. The findings indicate that oral MPA is a useful therapeutic agent in the management of minimal to moderate endometriosis, particularly when it is associated with infertility.