BackgroundHerlyn-Werner-Wunderlich syndrome is a rare congenital anomaly characterized by uterus didelphys, obstructed hemivagina, and ipsilateral renal agenesis. The most common presentation is abdominal pain, dysmenorrhea, and abdominal mass secondary to hematocolpos. We present the first case report on Herlyn-Werner-Wunderlich syndrome from Bangladesh.Case presentationA 15-year-old Asian girl presented with lower abdominal pain of 3 months’ duration. She had had menarche 3 months earlier and had a regular menstrual cycle with cyclical abdominal pain. Abdominal examination found a tender mass on the right iliac fossa. Further evaluation with ultrasound revealed distended endometrial cavity filled with complex fluid and nonvisualization of the right kidney. Pelvic magnetic resonance imaging showed absent right kidney and two separate endometrial stripes surrounded by endometrium and a muscular layer. The right endometrial cavity and cervix were distended with blood. This magnetic resonance imaging finding is consistent with Herlyn-Werner-Wunderlich syndrome with uterine didelphyis, right-sided hematometra resulting from obstructed hemivagina, and ipsilateral agenesis of the right kidney. The vaginal septum was resected for vaginoplasty. She was discharged 5 days after surgery and came for follow-up after 7 days. Vaginal examination revealed a healthy wound with no adhesion of the vaginal wall. She also informed us that she had started regular menstruation without any pain 30 days after the operation.ConclusionAn unusual presentation of regular menstruation and nonspecific abdominal pain delays the diagnosis, which can lead to complications such as endometriosis and infertility. Awareness is required; otherwise, misdiagnosis clearly can occur.