In vivo voltammetry was used in rats with brain ischemia induced by four-vessel occlusion to measure changes in dopamine metabolism via measurement of peak 2 (dopamine compounds) in the striatum. Changes in regional cerebral blood flow in the striatum were also assessed by means of a temperature-controlled thermoelectrical device. Peak 2 increased by 600-900% during 30 minutes of four-vessel occlusion, which may have reflected an ischemia-provoked increase in the release of dopamine and a disturbance in the outward transport of its metabolites. Following reperfusion by discontinuation of carotid occlusion, peak 2 rapidly decreased to below control values and then gradually increased, exceeding control values at 180-210 minutes after reperfusion. REgional cerebral blood flow in the striatum decreased to almost 0 ml/100 g/min during the ischemic period, transiently increased to greater than control values after reperfusion, then gradually decreased during the next 240 minutes. Since dopamine is known to have various effects on cerebral metabolism and blood flow, alterations in its behavior may contribute to changes in cerebral blood flow and to postischemic brain damage. In vivo voltammetry may be useful in the investigation of the pathophysiology of brain ischemia.