Duplicated uterus associated with unilateral imperforate vagina and ipsilateral renal agenesis is a very rare anomaly. We report a case of a 10-month-old female infant presenting with pus discharge from vagina, and discussed the embryologic and clinical features relevant to this interesting disease complex with a review of the past literature. Echographic and CT examinations demonstrated a right-sided cystic pelvic mass. IVP revealed a left slight hydronephrosis and non-visualizing right kidney. No right ureteral orifice was found at cystoscopy. Under anesthesia the mass and pus was aspirated. Under the diagnosis of Gartner's cystic duct and a right renal agenesis or dysplasia with or without ectopic ureter, we subsequently performed laparotomy. Surgical exploration revealed a duplicated uterus with a normal ovary, and the mass was an imperforate right-sided vagina which communicated through the uterus. The diagnosis was changed to a double uterus with right-sided imperforate vagina, then the vaginal septum was excised. The post-operative course was uneventful, and pus discharge and the left hydronephrosis have disappeared.