Numerous studies have identified the presence of endometriosis by its "classic" morphologic characteristics in high-risk patient populations. Recent histologic documentation of "subtle" laparoscopic appearances of this condition suggests that many of the earlier studies may have underestimated its prevalence in the general population. We evaluated the frequency of endometriosis in 86 women who denied having the symptoms typical of the condition and who underwent laparoscopy for other indications (acute pain, sterilization, etc.). Of those patients, 45.3% were found to have definitive evidence of pelvic endometriosis (stage I, 32.5%; II, 9.3%, III, 1.1%; IV, 2.3%). The exclusion of nine patients whose only laparoscopic indication was infertility or tubal occlusion resulted in a 44% finding of endometriosis, while 39% of the patients with documented fertility exhibited endometriosis. Forty-four percent of a subset of asymptomatic women undergoing laparoscopic evaluation prior to vaginal hysterectomy were found to have evidence of endometriosis; all but one had stage I, judged amendable to laser excision. The data suggest that endometriosis may be a more common peritoneal finding in asymptomatic, fertile women than previously believed.