In daily medical practice, we occasionally encounter patients with a foreign body in the urinary bladder. However, the identification of such a foreign body in an adolescent and the occurrence of an urethrocutaneous fistula caused by the foreign body are extremely rare. Only two cases have been reported previously. Herein we present a case of a foreign body in the urinary bladder and an urethrocutaneous fistula in a young patient. A 14-year-old boy with fever, left scrotal pain and urinary incontinence was referred to our department. Intravenous pyelography and micturition cystourethrography findings revealed a vesical foreign body and an urethrocutaneous fistula. He mentioned that he had inserted two dozen magnets into the urethra for masturbation one year previously. As the foreign bodies were spherical small magnets, we performed transurethral surgery and successfully removed the magnets. His postoperative course was uneventful and he was discharged from our department on the seventh day after surgery. Three months following surgery, the fistula had closed spontaneously.