Ischemic preconditioning (IPC) of the brain describes the neuroprotection induced by a short, conditioning ischemic episode (CIE) to a subsequent severe (test) ischemic episode (TIE). Most of the supporting evidence for IPC is based on histological assessment, several days after TIE. The aim of this study is to investigate if changes induced by IPC can be detected within 30 min of reperfusion following the ischemic episode. A rat model of "four-vessel