Twenty-six cases of hydrometrocolpos in infancy have been recognized during life or discovered at autopsy in this hospital since 1935.There were 10 infants with imperforate hymen or low obstructing vaginal membrane, 13 with atresia or stenosis of the vagina, and 3 with cervical stenosis or atresia.Although imperforate hymen was not associated with other congenital anomalies, all children with stenosis or atresia of the vagina or cervix had other congenital malformations, usually multiple and severe. Fistulae, imperforate anus, bicornuate uterus, and renal hypoplasia were especially common.The resulting anatomic complexity necessitates individualization of the radiologic diagnostic approach. It is clearly worth-while to obtain as complete preoperative definition of the anatomy as the condition of the child allows.