cerebral ischemia is an important event in clinical and surgical neurological practice since it is one of the diseases that most compromise the human species. in the present study 40 adult rats were submitted to periods of focal ischemia of 30, 60 and 90 min without reperfusion and animals submitted to a sham procedure were used as controls. we analyzed the levels of atp, malondialdehyde and caspase-3. no significant differences in the biochemical measurements were observed between the right and left brain hemispheres of the same animal in each experimental group. reduced atp levels were observed after the three periods of ischemia compared to the sham group. no significant increase in malondialdehyde or caspase-3 levels was observed. despite significant changes in atp levels, the results indicated cell viability in the ischemic region as shown by the low rates of lipid peroxidation and apoptosis, findings probably related to the lack of reperfusion.