Ninety-eight cases of congenital uterine malformations were diagnosed with hysterosalpingography (HSG). Symmetric uterine malformations, composed of bicornuate uterus, uterus didelphys and septate uterus, constituted 80% of the cases. Of them, 75% were of the bicornuate type. Infertility (55%) and a suggestion of cervical incompetence (24%) were the main indication for HSG. Premature deliveries (29%), spontaneous first-trimester abortions (24%), ectopic pregnancies (3%), abnormal fetal presentations (23%) and a high cesarean section rate (27.5%) occurred in those patients. The highest rate of first-trimester abortions (47%) and the lowest rate of term deliveries (21%) occurred in the group with T-shaped uteri as compared to a 7% rate of early abortions (P less than .05) and 61% rate of term deliveries (P less than .03) in the unicornuate uterus group. In 30% of the patients with uterine malformations, cervical incompetence was diagnosed. Improved obstetric outcomes occurred in patients treated with cervical cerclage. There was a statistically significant difference between the number of premature deliveries and spontaneous late abortions in the group without cerclage (50%) and that with cerclage (21%) (P less than .001).