Bladder tumor was suspected in 32 of 774 urinary bladders that were examined by transabdominal ultrasonography (US) from January 1988 to December 1990, and was confirmed on cytoscopic examination in 9 of the 32 cases. Diameter of the ultasonically detected tumors ranged from 0.5 cm to 8 cm. However, cytoscopy detected 5 tumors that had not been detected on ultrasonic examination, and 2 of them were subsequently diagnosed as malignant on the basis of histologic findings. Both malignant tumors were 0.3 cm in diameter. Thus sensitivity of US was 64%, while specificity is 80%, when compared with the cytoscopic findings. These results led us to believe that a synthetic judgment, based on urine cytology or other modalities in addition to US, was necessary in the screening of bladder tumors. Although the efficacy of US was too low to qualify it for use as an independent tool for screening for bladder tumors, it was considered that observation of the bladder should be added to the general US screening of abdominal organs.