Transabdominal wall ultrasonography in the study of the bladder tumours is a simple and athraumatic method. In this prospective study the ultrasonographic patterns considered allow the differentiation among three principal classes: I group: superficial tumours with intact bladder wall; II group: invading tumours with the disappearance of the bladder wall behind the tumour (it is not possible to differentiate a superficial muscle involvement to a deeper invasion); III group: tumours with extra-vesical extension. The ultrasonic stage grouping has been compared with pathological staging, in a series of 46 patients (1981-1982). The I group (superficial tumours), corresponding to Pis-P1 pathological stage, and the III group, corresponding to P4, have a good accuracy (85% and 87,5%). In the II group, corresponding to P2-P3, the accuracy is less (72%) and it is not possible to differentiate between the two pathological stages. Transabdominal wall ultrasonography should be the first investigation in the preoperatory staging of bladder tumours.