Laparoscopy has greatly evolved over the years. More recently, retroperitoneoscopy has gained wide acceptance as the preferred approach for simple and complicated nephrectomies. We report on a 12 year-old girl who underwent a left nephrectomy on a horseshoe kidney through a retroperitoneoscopic approach using the harmonic scalpel for dissection and isthmus division. The operation was successful, recovery uneventful, and the patient was discharged 24 hrs post operatively, with excellent cosmesis. Retroperitoneoscopy can be considered if ablative surgery is contemplated in a horseshoe kidney, with adequate preoperative evaluation and solid retroperitoneoscopic surgical experience. The use the harmonic scalpel was greatly beneficial for the overall success of this complicated intervention.