We report the case of a 7-year-old girl with a single ectopic ureter who was treated with retroperitoneoscopic nephrectomy for a chief complaint of urinary incontinence. Preoperative CT showed a contrasted dysplastic kidney of 1cm in the renal fossa and a left ureteral opening into the vagina. Retroperitoneoscopic left nephrectomy was conducted with opening of the lateroconal fascia to enable identification of the dysplastic kidney. No intraoperative complications were encountered. Urinary incontinence improved immediately after surgery. This case shows that a retroperitoneal approach can be used in nephrectomy if the position of the kidney can be determined preoperatively.