Uniformity of the echo return from the bladder wall has been demonstrated in experimental and patient studies. An infiltrating bladder tumor disrupts this uniformity. The studies also showed a sharp bladder wall outline that was less echogenic, probably representing the perivesical fat. Thus, the ultrasonographic estimation of tumor staging as related to the depth of infiltration of the bladder wall. A staging accuracy of nearly 100 per cent was found for deep tumors of the bladder wall or those penetrating extravesical structures. On the other hand, many superficial tumors were overstaged, their staging accuracy being only slightly higher than 55 per cent. However, in view of its accuracy in staging infiltrating tumors, in addition to its other already known advantages, ultrasound seems to be the method of choice in preoperative staging of tumors. We believe that it should be included in the routine protocol and should follow diagnostic cystoscopy in all cases of tumors larger than 0.5 cm.