Eighty patients with different stages of genital endometriosis were treated with Zoladex, a gonadotrophin-releasing hormone analogue in a depot formulation, injected subcutaneously every 4 weeks. The stages of endometriosis (I-IV) were classified according to the revised American Fertility Society recommendations (AFS criteria) via pelviscopy before and after 6 months of treatment. Fifty-eight second-look pelviscopies were performed with the following objective changes after (before) treatment: Stage IV 0 (3); Stage III, 2 (13); Stage II, 12 (30); Stage I, 19 (12). Twenty-five patients presented with Stage 0 after therapy and were healed. All 57 symptomatic patients showed a subjective response to Zoladex therapy with a significant decrease of the total pelvic symptom score. Thirty-eight patients with infertility wished to become pregnant and so far 16 (40%) have conceived. During therapy, the serum concentrations of luteinizing hormone, follicle stimulating hormone, estradiol and progesterone were significantly suppressed. All patients were amenorrhoeic after 1-2 injections. Restoration of ovarian function with resumption of menstruation occurred within 57-92 days after the last injection of Zoladex (1-2 months after end of treatment). Side-effects were minimal and were those expected of the hypo-oestrogenic state, such as hot flushes, vaginal dryness and decrease of libido.