The technique of selective renal occlusion phlebography using Swan-Ganz or Dotter-Lucas balloon catheters is described. The Swan-Ganz catheter is introduced into the femoral vein with the aid of a Cordis introducer system. The Dotter-Lucas balloon catheter is inserted via the same route using a combination of either a Desilets-Hoffman or Edslab introducer, along with a Gebauer introducer. Occlusion of the renal vein is achieved by insufflation of the balloon with air or injection of saline or dilute contrast media into the balloon. Selective renal occlusion phlebography was performed in 116 patients in order to exclude renal vein thrombosis, to delineate poorly vascularized renal masses, to determine the venous involvement of a renal tumor, and to assess the patency of splenorenal shunts. Renal occlusion phlebography optimizes the retrograde opacification of the renal veins. It has value in the delineation of poorly vascularized renal masses and in the determination of the venous involvement of renal and retroperitoneal tumors, and it would seem to be the method of choice for demonstrating the patency of surgical splenorenal shunts. Further enhancement of venous opacification by the combination of temporary arterial vasoconstriction with angiotensin (pharmaco-occlusion phlebography) and venous balloon occlusion is useful in some cases.