A method permitting percutaneous catheterization and temporary balloon occlusion of the human renal artery with a 5-F-Swan-Ganz-Catheter is presented. When properly performed, the arterial occlusion is reliable, low in complications, and less traumatizing to the vessel than external clamp occlusion. The technique was employed in 112 patients for occlusion of the renal artery prior to tumor nephrectomy, for attaining stop-flow conditions for improved nephrophlebography, for preventing the reflux of emboli at transarterial embolisation of inoperable kidney tumors, or, combined with simultaneous hypothermic perfusion via the second lumen of the catheter, in extensive kidney surgery necessitating ischemia. Particularly this last range of application offers new possibilities for in-situ surgery of the kidney, as it renders dissection of the renal pedicle and cumbersome surface cooling of the kidney unnecessary.