Dimethyl sulfoxide (DMSO) has a variety of properties suggesting that it may be a useful agent in the management of central nervous system trauma and stroke. The purpose of this investigation was to determine the systemic and cerebrovascular effects of varying doses of DMSO in a normal animal. Five mongrel dogs were subjected to a constant infusion of 100% DMSO at a rate of 4 g/kg/hour. Using the radioactive microsphere technique, we measured blood flow before giving DMSO and after 2, 4, 6, and 8 g of DMSO per kg had been infused. After 2 g/kg had been given, hemolysis was evident and the intravascular volume increased, resulting in a lowered hematocrit. The cerebral metabolic rate of oxygen remained stable throughout the study. The total cerebral blood flow increased over 20% after a cumulative dose of 6 g/kg. Blood flow to the cerebellum and brain stem was unchanged, while flow to the caudate nuclei and cerebral hemispheres increased. There was a reduction in flow to the corpus callosum and spinal cord. DMSO caused an increase in the cardiac index accompanied by a large increase in the right and left ventricular blood flows, but a reduction in kidney flow. The relationship of this redistribution of blood flow, especially within the cerebrospinal axis, to the therapeutic effects of DMSO bears further investigation.