Angiographic examination of the pulmonary arteries is an established diagnostic technic (6, 8, 15). It may be accomplished by the injection of contrast material into one or more systemic veins, the right atrium, the right ventricle, or any portion of the pulmonary arterial system. If detailed examination of a localized portion of the pulmonary arterial tree is desired, selective pulmonary arteriography may be performed by advancing a catheter into a pulmonary artery branch (4, 5, 10). Satisfactory visualization of the pulmonary veins is more difficult. Pulmonary venous angiography (phlebography) usually has been achieved indirectly during the passage of contrast material through the pulmonary veins after injection into a systemic vein, a right heart chamber, or a pulmonary artery (11, 16). At best this method fails to provide sufficiently intense opacification of these veins for their detailed examination. To enhance the precise evaluation of pulmonary veins, the following experimental technic for selective phlebography was developed. Technic Mongrel dogs weighing 9 to 20 kg. were anesthetized with sodium pentobarbital intravenously (27 mg./kg.). A common carotid or common femoral artery was exposed surgically, and an end-hole catheter was introduced through a small arteriotomy. Selective catheterization of a pulmonary vein was accomplished by advancing the catheter successively through the ascending aorta, left ventricle, and left atrium. When the common carotid artery was the route of entry, rotation the catheter tip in an anterior direction as it approached the aortic arch prevented it from passing into the descending aorta. The left ventricle was entered by advancing the catheter gently against the resistance met at the aortic valve. In the ventricle a distal loop was formed by pushing the catheter against the ventricular wall. The catheter was then rotated so that its tip presented posteriorly; it was advanced and withdrawn alternately until the tip or a loop entered the left atrium. Finally, the tip of the catheter was maneuvered into a pulmonary vein. Optimum of the tip for selective phlebography was about 2 or 3 cm. dorsal to the posterior cardiac contour. The use of a catheter of moderate stiffness appeared to be an important factor in the successful catheterization of the left atrium. When catheters of lesser stiffness were employed, they buckled before a loop could be formed. The left atrium could be entered with a Shirey3 catheter, but selective catheterization of a pulmonary vein was more difficult, and opacification of distal veins was more satisfactory with an end-hole catheter than with a multiple side-hole catheter. During catheter manipulation in the left ventricle, considerable ventricular arrhythmia occurred. The rhythm returned to normal, however, when the catheter was in final position.