The effects of the xanthine derivative propentofylline [3-methyl-1-(5'-oxohexyl)-7-propylxanthine] were measured on local cerebral blood flow and glucose utilization in the rat using quantitative autoradiographic techniques. A dose of 0.5 mg/kg/min i.v. produced increases in local cerebral blood flow and minimal effects on glucose utilization in the majority of cerebral structures measured. A higher dose of propentofylline (1.5 mg/kg/min) produced an overall increase in local cerebral blood flow and a marked reduction in glucose utilization. Furthermore, propentofylline increased the average ratio of blood flow per unit glucose utilization and thus is capable of increasing cerebral blood flow in excess of metabolic demand. While the mechanism of action of this compound has not been fully defined, it is possible that its cerebrovascular and cerebral metabolic effects can at least partially be explained by a blockade of adenosine uptake. These actions of propentofylline on cerebral blood flow and metabolism may play a role in protecting neuronal tissue under hypoxic/ischemic conditions in the brain.