Conservative or radical surgical treatment, steroidal hormones to produce pseudopregnancy, and danazol are all being used to relieve the symptoms of endometriosis or to treat the infertility that frequently accompanies it. The choice of therapy should be determined by the patient's desires and the extent of her disease. Our approach to treating this condition is as follows: Young patients with symptoms who wish to delay childbearing: Treat with danazol 400 mg to 600 mg per day for 6 months to induce regression of the disease and relieve symptoms. Once that is achieved, encourage use of low-dose oral contraceptive or the minipill to minimize progression of the disease. Delay surgical therapy, if needed, until the patient wishes to conceive . Infertile patients with mild endometriosis: Treat medically with danazol, 400 to 600 mg per day for 6 months. Then encourage attempts to conceive for 9 to 12 months. Patients who fail to become pregnant should have repeat laparoscopy to assess further the need for conservative surgical treatment. Infertile patients with moderate or greater disease: Treat with conservative operation. If conservative operation is not done at the same time as the diagnostic laparoscopy, give danazol for 2 to 3 months preoperatively to decrease the number and the size of the endometriotic areas, minimize the extent of operation, and avoid traumatizing the corpus luteum. Patients who remain infertile after conservative surgical treatment: Treat with danazol for approximately 6 months and then try for conception. A second conservative operation will have a modest chance (less than 30 percent) of success. If severe symptoms persist, perform definitive operation. Patients who are not desirous of further childbearing: Treat with definitive surgical treatment if symptoms are severe and the quality of life is impaired. Patients who want to postpone or avoid a major operation may benefit from a course of danazol. Patients with endometriosis involving the organs outside the pelvis: Advise total abdominal hysterectomy and bilateral salpingo-oophorectomy. For patients who desire further childbearing, danazol treatment has been reported to be successful in pulmonary, intestinal, and ureteral involvement. Endometriosis is a poorly understood, ubiquitous, and progressive disease with inconsistent clinical presentation and poorly standardized therapy.(ABSTRACT TRUNCATED AT 400 WORDS)