Leiomyosarcoma of the urinary bladder in childhood is uncommon. We reported bladder leiomyosarcoma in a 10-year-old boy. He had underwent the extirpation of the tumor and performed adjuvant chemotherapy in combination with radiotherapy according to the Intergroup Rhabdomyosarcoma Study-4 regimens. He had no evidence of recurrence of disease after 3 years.