Hydrocolpos is the result of vaginal obstruction and can become an emergency in the newborn period. The treatment of imperforate hymen is well defined, but the treatment of vaginal atresia is more complex. We encountered two cases of hydrocolpos secondary to distal vaginal atresia, that were operated on in the first days of life. One baby had distal atresia without persistance of urogenital sinus. Surgery combining abdominal perineal approaches and a posterior vaginoplasty was carried out. The second baby had hydrocolpos with persistance of urogenital sinus. Drainage through the sinus was unsuccessful because the baby developed sepsis by trapping urine in the uterus. Finally an abdominoperineal vaginal pull-through was successfully done. The embryology and literature are reviewed. The classification, indications and surgical technique are discussed.