Selective renal venography has been widely applied in the diagnosis of renal vein thrombosis (3, 9, 12, 15) and in the evaluation of renal blood flow in hypertension (1). However, while arteriography has been recommended for evaluating conditions of the renal parenchyma (7, 8), the use of venography in this area has been generally ignored. A review of over 100 selective renal venograms obtained in our department indicates the great value of this method and its simplicity and safety. Technic Entry is percutaneous via the femoral vein. A flexible, radiopaque catheter large enough to permit sufficiently rapid injection (e.g., Kifa or B-D Formacath Green or Gray) is used. In the right renal vein, a simple curve, about 50 per cent wider in diameter than the inferior vena cava, usually allows the catheter tip to advance to the renal hilus. The same catheter can be placed in the mouth of the left renal vein and inserted to the left hilus with aid of a guide wire. Alternately, a straight or slightly curved catheter can be introduced into both renal veins with a controllable guide wire (U.S.C.I.-Mueller, or Cook). For selective catheterization of segmental veins either a coaxial catheter combination (Clay-Adams PE 160 through BD RPX 082) or a controllable guide wire system is used. Methylglucamine diatrizoate or iothalamate 60 per cent (Renografin 60 or Conray 60) is the usual contrast media. When an injection rate problem exists, sodium iothalamate 66.8 per cent (Conway 400) diluted with half its volume of saline is used. This mixture has a low viscosity. Highly concentrated media often recommended (1) are not required. The injection rate must overcome both the renal blood flow and the reservoir function (4) of the renal veins. For normal kidneys these are approximately 6–10 ml per second, and 25–40 ml, respectively. An injection of 35–60 ml in two seconds into the main renal vein at kidney hilus is recommended. Much smaller doses will suffice for segmental injections, for kidneys with decreased circulation, and for artificially reduced flow. When selective venography is obtained at the same time as selective arteriography, 10 micrograms of epinephrine is injected into the renal artery about ten seconds before the venogram (10, 13). This not only stops arterial flow almost entirely but also increases venous tone (6), thus reducing the size of the blood reservoir to be replaced. Since tumor vessels do not respond, epinephrine is not useful in improving visualization of the veins draining renal carcinomas. Serial films are obtained at a rate of 2–3 per second for two seconds, and 1 per second for an additional four seconds. Cine recording does not give adequate detail. Results The quality of the venogram depends almost entirely upon the degree to which the technic is performed satisfactorily.