To discover the exact incidence of congenital uterine anomalies among infertile patients, hysterosalpingography was performed on 1,200 married women with a history of repeated reproductive wastage. Out of 1,200 hysterosalpingographies, 188 revealed congenital uterine anomaly (15.7%). The degree of uterine cavity deformity in the anomalies was evaluated during hysterosalpingography using the X/M ratio. This indicated that the incidence of repeated spontaneous abortion in cases with low-grade anomalies is as high as the incidence among cases with more severe anomalies. A significant improvement in maintaining pregnancy was observed after metroplasty; more than 84% of postoperative pregnancies were successfully maintained, whereas none of the 233 presurgical pregnancies had lasted full term. As a control group, 47 other women with anomalies were randomly chosen, and their subsequent pregnancies were monitored, without metroplasty. Of their pregnancies, 94.4% terminated spontaneously before 12 weeks of gestation.