Selective catheterization of blood vessels aided by fluoroscopy has been a common procedure in man for the last ten years. Special catheterization technics have also been developed for some animals, especially the dog and cat (2, 4, 6). In 1933, Rousthöi (7) performed his classical experiments with arterial catheterization in the rabbit. Introducing a cannula or a catheter into the common carotid artery and gently passing it down into the aorta, he was the first to visualize the coronary arteries in a living animal by an injection of contrast material nonselectively into the ascending aorta. The present report describes a technic for selective arterial catheterization in the rabbit. Method and Material The technic employed is as follows: An ear vein of the rabbit is cannulated with a pediatric scalp vein needle and Diabutal or urethane anesthesia is administered. Physiologic saline with heparin (1,000 I.U. per 500 ml) is used for rinsing the catheter. The catheter employed is made of a small radiopaque vinyl tubing (XRVX020, radiopaque sterile medical grade vinyl tubing, Becton-Dickinson and Co., USA, I.D./O.D. = 0.5 mm/0.9 mm). A slightly larger catheter is used for the brachiocephalic arteries (XRVX036, I.D./O.D. = 0.7 mm/1.2 mm). The tip of the catheter is tapered by heating it over an alcohol lamp and then pulling it. Boiling water is used to mold the tip and to straighten the rest of the catheter. A straight catheter, small and large hooks, and an “S” catheter have been employed (Fig.1). The outer diameter of the tip measures about 0.5–1.0 mm. The catheter is introduced through the femoral artery by a cut-down technic (4). Spasm of the femoral artery, which frequently occurs with manipulation, is relieved by spraying Xylocaine 2 per cent (Astra) on the artery. The smallest possible segment of the artery should be exposed and no large side branches tied. When the catheter is introduced, the tip must be straightened to pass up the femoral artery. In the aorta, however, most of the curve will reappear. The catheterization procedure should not be unduly protracted since the catheter may soften and lose its shape. The animal is supine while fluoroscopy is performed with an image intensifier and a mirror. The Vidicon TV system will not give high enough resolution for the fine detail desired. An Orthicon TV system with magnification, however, is satisfactory. A three-phase roentgen apparatus (Siemens) with a small focal spot (0.3 X 0.3 mm) and high-speed rotation of the anode is employed. The film-focus distance is 100 cm. There is no grid. Screen and nonscreen cassettes are utilized. Stereoscopic films are sometimes taken to facilitate separation of the different branches. The contrast material used for the selective injections is Renografin 60 per cent or 76 per cent. Results Ten large white rabbits (New Zealand strain) were studied by this method of selective arteriography.