Abstract: Objective To explore the role of p38 mitogen-activated protein kinase (p38MAPK) in the development of cerebral hypoxic preconditioning. Method Healthy adult male BALB/C mice weighing18~20g were randomly divided into 7 groups as follows: normoxic control (H0), early (H1~H4) and delayed (H5 and H6) hypoxic preconditioned mice groups. SDS-PAGE, Western blot and Gel Doc imagine systems were applied to quantitatively analyze the levels of p38MAPK phosphorylation and protein expression in the brain of mice. Results We found that the phosphorylation levels of p38MAPK increased in cortex, hippocampus and hypothalamus of mice both from early (H1-H4) and delayed (H5 and H6) hypoxic preconditioned groups, and the statistic significance (P<0.05, n=6 for each group) could find in cortex and hippocampus of mice from H2~H6, and hypothalamus of mice from H3~H6 groups in comparison to H0 (n=6), respectively. However, there were no significant changes in p38MAPK protein expression in cortex, hippocampus and hypothalamus of hypoxic preconditioned mice from H1-H6 groups when compared with H0 (n=6). Conclusion These results suggest that the increased phosphorylation (activation) of p38MAPK, not protein expression, might be involved in the development of cerebral hypoxic preconditioning of mice.