OBJECTIVE: To study the expression of apoptosis regulated genes bcl-2 and bax nocoprotein expression and its significance in rat cerebral ischemic preconditioning. METHODS: With immunohistochemical assay, bcl-2 and bax expression were studied in rat brains which were divided into four groups: the sham-operation control group, the cerebral ischemic group and the cerebral ischemic preconditioning group. RESULTS: Bcl-2 oncoprotein was induced in cerebral ischemic preconditioning control group. Bax oncoprotein expression had no obviously difference in four groups. CONCLUSIONS: The expression of bcl-2 and bax oncoprotein after sublethal ischemic preconditioning might be associated with the preconditioning protection against neuronal damage following subsequent lethal ischemia.