Retroperitoneal cystic lymphangiomas are extremely rare and the majority are symptomatic during childhood. Although benign, they can compress and infiltrate vital structures. Surgery is curative but is associated with a high complication rate. An alternative treatment strategy is image-guided percutaneous catheter drainage of the lymphangioma followed by sclerotherapy. Resolution of a large retroperitoneal cystic lymphangioma in a 4-year-old child treated by this technique is reported. To our knowledge, this technique has not been previously described in this condition and we believe that it offers significant advantages over surgery.