The adverse effects on brain tissue of contrast media used for cerebral angiography have been reported in considerable detail. However, the physiological alterations which may occur require further investigation for a better understanding of possible complications. In this preliminary report the cardiovascular effects of iodopyracet (Diodrast) and of diatrizoate (Hypaque) are discussed. Intracarotid iodopyracet injections produce mainly a vascular necrobiotic change affecting particularly the arterioles, followed by ischemic necrosis of surrounding parenchyma.1Alteration of the blood-brain barrier was demonstrated experimentally in rabbits by Broman and Olsson2by the passage of trypan blue into the brain parenchyma from the cerebral circulation. They postulated a chemotoxic effect on vascular endothelium, producing vasospasm, with resulting edema, vascular engorgement, and punctate hemorrhages in the central portions of the damaged areas. The intensity of injury varied with the time the contrast medium remained in contact with the involved tissues. Bassett, Rogers, and Cherry