The changes of calcium and magnesium content in brain tissue (BCa;BMg) and in the mitochondria (MCa,MMg) and calmodulin content in the cortex and hippocampus (CCaM,HCaM) were determined in the rats with 4-vessel-ligation cerebral ischemia.And then the therapeutic effects of nimodipine were observed during ischemic and.reperfusion stages of the brain.It was found that BMg and BMg were decreased and CCaM HCaM increased during both the ischemic and reperfusion stages and BCa and MCo were increased during the reperfusion stage.The fact that calcium content was only increased during the reperfusion stage indicates that the influx of calcium plays an important role to precipitate injury during the reperfusion stage.Adminstration of nimodipine could prevent the increase of calcium and calmodulin and the decrease of magnesium after cerebral ischemia.