This 6-month clinical trial with an additional 12-month follow-up compared the effects of treatment with the gonadotropin-releasing hormone agonist nafarelin and the androgenic agent danazol on lipids and calcium metabolism in women with endometriosis. Of the 23 women who completed the double-blind, double-dummy study, 15 were treated with nafarelin and 8 with danazol. Investigators observed the effects of both agonists on estradiol levels, American Fertility Society endometriosis scores, and side effects. Results indicate that nafarelin seems to be a good alternative to other medications for the treatment of endometriosis and has an acceptable side-effect profile, including metabolic effects. © 1990.