We reviewed the case records of all women (N = 748) who underwent laparoscopy for infertility in our department from 1985-1990. The patients were divided into two groups, cases and controls, according to the presence of nonobstructive müllerian anomalies (N = 198) or absence of such anomalies (N = 545); women with obstructive müllerian anomalies (N = 5) were excluded. The patients were analyzed for the presence of endometriosis, malformation class, and productive history. The frequency of endometriosis was 30.8% in the women with nonobstructive müllerian anomalies, versus 38.5% in the controls (P = .209). Among the subjects with unicornuate uterus, the prevalence of endometriosis (55%) was significantly greater compared with the patients with other nonobstructive müllerian anomalies (28%) (P less than .05), but not compared with the controls (38.5%). Overall, no differences were observed in the frequency of endometriosis between infertile women with and without nonobstructive müllerian anomalies. Our results seem to exclude a common pathogenetic factor underlying endometriosis and nonobstructive müllerian anomalies.