The obstetric risk associated with congenital uterine malformations was studied in a group of 67 women who had undergone hysterosalpingography (HSG) during an eight-year period. HSG was performed to investigate primary (21% of the cases) and secondary (19%) infertility (group 1) or recurrent early fetal loss (60%) (group 2). The study group was compared with a random control group of 130 patients with HSG-proven normal uteri, matched for the presenting symptom. Prematurity and intrauterine fetal death were found to be significantly more common (P less than .05) for women in group 1 with uterine anomalies. The mean birth weight for preterm infants (less than 37 weeks) was significantly lower (P less than .01) for women with malformed uteri. The incidence of antepartum bleeding during pregnancy (P less than .01), breech presentation and cesarean section (P less than .001) was significantly higher for the study group. Premature rupture of the membranes was diagnosed more frequently (P less than .05) only in group 1. Patients with congenital uterine anomalies are a high-risk obstetric group. Primary infertility may be a more common presenting complaint in women with uterine anomalies than previously recognized.