Müllerian malformations represent a wide spectrum of anomaly of the female reproductive tract, usually detected at birth or at puberty. The presence of uterus didelphys and obstructed hemivagina, associated with ipsilateral renal agenesis, is known as Herlyn-Werner-Wunderlich syndrome, a rare congenital anomaly. Two cases of uterus didelphic and hematometra caused by vaginal septum are reported; the girls had a delayed diagnosis due to absence of a specific clinical feature. Clinicians must be aware of the existence of these malformations. An adequate radiological study is mandatory to assess the anatomic conformation, and to optimize the therapeutic procedures.