The powerful vasoconstrictor effect of minute intra-arterial injections of epinephrine on normal arteries can be demonstrated readily by angiography. On the assumption that tumor vessels might not respond as readily to this vasoconstrictor, Abrams, Boijsen, and Borgström (3) proposed the use of epinephrine to direct contrast material selectively into neoplastic tissue. Subsequently, in a case reported by Abrams (1, 2), this relative increase in tumor circulation was demonstrated in a patient with renal-cell carcinoma. A study of a group of patients undergoing selective renal angiography with epinephrine, in addition to substantiating Abrams' hypothesis, reveals that the effect of this drug is much more complicated than was proposed previously. Other uses for epinephrine in angiography are suggested by this investigation. Methods and Materials Seventeen patients undergoing retrograde femoral selective renal angiography were studied with epinephrine. Six had malignant tumors which derived their blood supply from the renal arteries; 1 had leukemic infiltration of the kidney; 5 had benign renal cysts; and in 5 there was no angiographic evidence of a renal mass. In each case, following aortography a selective injection of 6 to 10 cc of 40, 60, or 76 per cent Renografin was made before and 20 to 45 seconds after the intra-arterial injection of 5 to 25 μg of epinephrine in 10 cc normal saline, and serial films over a six-to twenty-second period were obtained on a Schönander cut-film changer. The patient's pulse and blood pressure were monitored, and his subjective reaction to the injection was evaluated. Results Following the injection of epinephrine, marked slowing of flow in the normal renal artery was manifested by an increased density of contrast material and a spill of some of the injected contrast agent into the aorta. Frequently, capsular, intercostal, subcostal, lumbar, and adrenal arteries were filled (Fig. 1). The main renal artery was unchanged in size, but a sharp tapering was noted in the primary branches at the level of the renal pelvis. Beyond this point the flow was very slow, with contrast material entering the markedly narrowed secondary branches only after six to fifteen seconds. With adequate doses and timing there was little visualization of smaller arteries, and the renal capillary and parenchymal phases were almost absent. A small but consistent 2 to 8 mm reduction in length of the kidney was disclosed. Vessels supplying renal tumors demonstrated less response to epinephrine than normal renal tissue, although by no means were they unaffected. When the blood supply to the neoplasm arose from a main renal artery, there was a relative prominence of the tumor stain along with absence of the normal parenchymal phase (Fig. 2).