Regional cerebral blood flow (CBF) was measured autoradiographically in the recovery period following 15 min of forebrain ischemia in rats pretreated with either nimodipine (0.1 mg kg-1) or vehicle. The results showed that although nimodipine increased postischemic CBF, the flow enhancement was regionally heterogeneous, sometimes resulting in zones of gross hypoperfusion and overt hyperemia within the same structures. This patchy improvement of delayed postischemic hypoperfusion was not accompanied by recovery of sensory evoked responses, and return of EEG activity was not enhanced.