A study was carried out of the distribution and density of the neurons remaining in the gerbil cerebral cortex following two 10-min periods of ischemia at either 3-, 5- or 48-h intervals. As the interval between the periods of ischemia increased, the ischemic injury was reduced from severe to milder infarction, and further from more to less intense disseminated selective neuronal necrosis. This model is suitable for studying the mechanisms of transition from selective neuronal necrosis to infarction at the threshold level of infarction.