Fourteen dogs were subjected to temporary occlusion of the portal vein. Electrocardiographic changes suggestive of epicardial or transmural necrosis of the high lateral region of the left ventricle and of subendocardial ischemia, were found in 55 per cent of the dogs. These electrocardiographic changes were accompanied by a significant rise of plasma GOT. Myocardial sections showed areas of multifocal necrosis, extending from endocardium to epicardium, with predominance in the lateral and anterior wall and pillars of the left ventricle and interventricular septum.