OBJECTIVE To compare the efficacy of leuprolide and continuous oral contraceptives in the treatment of endometriosis-associated pain. METHODS Prospective, randomized, double-blind controlled trial. METHODS Academic medical centers in Rochester, New York, and Boston, Massachusetts. METHODS Forty-seven women with endometriosis-associated pelvic pain. METHODS Forty-eight weeks of either depot leuprolide, 11.25 mg IM every 12 weeks with hormonal add-back using norethindrone acetate 5 mg orally, daily; or a generic monophasic oral contraceptive (1 mg norethindrone + 35 mg ethinyl estradiol) given daily. METHODS Biberoglu and Behrman (B&B) pain scores, numerical rating scores (NRS), Beck Depression Inventory (BDI), and Index of Sexual Satisfaction (ISS). RESULTS Based on enrollment of 47 women randomized to continuous oral contraceptives and to leuprolide, there were statistically significant declines in B&B, NRS, and BDI scores from baseline in both groups. There were no significant differences, however, in the extent of reduction in these measures between the groups. CONCLUSIONS Leuprolide and continuous oral contraceptives appear to be equally effective in the treatment of endometriosis-associated pelvic pain.