Pentoxifylline 0.3--30 mg/kg was given intravenously to six dogs under nitrous oxide anesthesia. Cerebral blood flow was measured with a sagittal sinus outflow technique, cerebral oxygen consumption was calculated from the a-v difference, and metabolite levels were determined in biopsies of cerebral cortex. Pentoxifylline failed to influence cerebral blood flow or oxygen consumption. There was no increase in cerebral levels of phosphocreatine, ATP or total adenine nucleotides; the only significant effect was higher glucose levels in dogs given pentoxifylline (4.49 +/- 0.39 mumol/g vs 2.21 +/- 0.18 mumol/g). The latter has previously been reported to be deleterious during cerebral ischemia. Pentoxifylline thus failed to have any significant influence upon cerebral blood flow or metabolism in the dog likely to be of benefit during cerebral hypoxia or ischemia.