To determinate the adequate method of treatment for bladder tumors and to establish the prognosis, “Staging” plays a most important role.<br>With the presacral method, 600ml of oxygen was injected into the perivesical space and 100ml of air was instilled into the empty bladder.<br>Then according to the percutaneous method of Seldinger, a catheter was introduced into one of the femoral arteries, and was flushed with 40ml of 76% Urografin at the level of aortic bifurcation.<br>Serial angiography was then taken and ten films have been exposed at the intervals of 1/2 second. Pathological findings that have been obtained are:<br>1) Increase of vascularity on the side of the tumor 2) network formation in the tumor region 3) corkscrew vessels in the tumor region 4) tortulous vessels in the tumor region 5) decrease or vanishing of the vascularity in the center of the tumor in some cases 6) dense, sustained blush of the tumor region (tumor stain) 7) several changes from proximal to distal portion of the vesical artery 8) vessel-widening on the side of the tumor 9) vessel-displacement on the side of the tumor 10) the growth of a new blood vessel which stems from the healthy side and supplies the tumor 11) rapid visualization of the venous phase on the side of the tumor 12) disarrangement of the vascularity on the bladder wall, especially in the capillary phase 13) parieto-visceral anastomosis in the internal iliac artery.<br>The follow up histopathological examinations have been done on 18 cases to evaluate the accuracy of the X-ray diagnosis, and 15 cases were proved to be accurate. Out of the 13 pathological findings mentioned above, 1)-6) seem to be due to the tumor mass, and 7)-13) due to tumor infiltration, especially 11)-13) to deep infiltration. The method and the pathological findings are discussed, and some interesting cases are presented.