Transrectal ultrasonography is a specially devised technique to obtain clear tomograms of the intrapelvic organs, such as the prostate, urinary bladder and seminal vesicles. We used this technique to evaluate 64 patients with bladder tumors. The results were compared with histological findings after exploratory surgery. Ultrasonograms of these tumors were estimated on the basis of bladder wall irregularity, bladder deformity, bladder capacity and extravesical spread of tumor. Each tumor stage showed characteristic ultrasonic features. Extravesical spread of tumor, which was observed in 67 percent of stage D tumors, proved to be an important finding to distinguish stage D tumours from other tumor stages. We suggest these features as diagnostic criteria for ultrasonic staging of bladder tumors.