Mullerian duct malformations were found in 8% and Asherman syndrome in 4.8% of 537 infertile women undergoing hysterosalpingogram and/or hysteroscopy among 840 consecutive infertile couples evaluated. Among the 43 patients with mullerian duct malformations and the 26 with Asherman syndrome, seven had both mullerian duct malformations and Asherman syndrome (16 and 29%, respectively). This association was highly significant (P less than .005), especially for those patients with a septate uterus (P less than .001). Secondary infertility was present in 44% of the 840 infertile couples; 41% of the 537 women undergoing hysterosalpingogram and/or hysteroscopy and 44% of the patients with mullerian duct malformations versus 81% of those with Asherman syndrome (P less than .001). Prior reproductive performance was dismal for the patients with Asherman syndrome and/or mullerian duct malformations, and among all classes of mullerian duct malformations, and among all classes of mullerian duct malformations. The predisposing and causative factors leading to Asherman syndrome can be observed with mullerian duct malformations and a strong association in this population of infertile couples is reported for the first time.