Our results showed that cerebral I/R increases the expression level of caspase-3 and Bcl-xl as well as the ratio of Bax to Bcl-2, while administration of 100 mg/kg kaempferol for 3 days decreased the expression levels of caspase-3 and Bax proteins and increased the expression levels of Bcl-2 and Bcl-xl proteins in ischemic penumbra, resulting in an increase of the Bcl-2 to Bax ratio and the inhibition of the occurrence of apoptotic events after cerebral ischemia-reperfusion. The gene discussed is BAX; the disease is brain ischemia.