A 9-year-old girl was discovered to have had a huge retroperitoneal mass causing moderate hydronephrosis and anterior displacement of the right kidney and which was found on a renal ultrasonographic examination. A series of examinations including (1) IVP, (2) abdominal computed tomography, (3) MRI and (4) incisional biopsy revealed a giant dumb-bell shaped retroperitoneal ganglioneuroma with intraspinal involvement. Secondary scoliosis was also noticed. We successfully resected the huge ganglioneuroma of the right retroperitoneum in a two stage procedure; her postoperative course was uneventflu.