Primary osteosarcoma of the bladder, together with transitional cell carcinoma, occurred in a 74-year-old female presenting with haematuria and lumbago. She was treated with chemotherapy and radical cystectomy. Though it was conceived to be curative, she died of a recurrence 5 months after the operation. Primary osteosarcoma of the bladder is an unusual and highly malignant disease. In spite of radical therapy, the outcome has been dismal with some exceptions.