Abstract: 【Abstract】 Objective To explore the expression changes of mitogen extracellular kinase (MEK) in injured lung after brain ischemia in rats. Methods Adult SD rats were assigned randomly to sham operation group and brain ischemia lung injury (BILI) group. Rats in BILI group were subjected brain ischemia and allowed to survived 3 d. Pathalogical changes in lung were indicated by HE staining. The MEK expression was determined by RT-PCR and Western blot technique. Results After brain ischemia, the bulk of inflammatory cells invaded into lung were observed. Upregulated level of MEK mRNA and protein were found at 3 days after ischemia (P<0.05). Conclusion The upregulated expression of MEK implied that the MEK may play some roles in lung injury after brain ischemia.