We report a rare case of malignant schwannoma arising from urinary bladder wall. The patient presented with progressive abdominal distension for 3 months. The preoperative IVP, barium enema and CT scan showed a huge, cystic tumor mass occupied the lower abdominal cavity. The operative finding revealed a well encupsulated soft tumor about 20X15 cm in size which connected with bladder wall by a stalk. Malignant schwannoma was diagnosed by histological and immunohistochemical studies. A review of the literature on malignant schwannoma was included.