Objective:To investigate the mRNA and protein expressions of Rac1 and HIF-1α in human esophageal squamous cell cancer Eca109 and the effects on the cell proliferation of Eca109. Methods:The mRNA and protein expressions of Rac1 and HIF-1α were detected by semi-quantitative RT-PCR and Western blot under hypoxia;The expression of HIF-1α mRNA and the cell proliferation were detected by semi-quantitative RT-PCR and MTT in Eca109 cell line with the use of Rac1 specific inhibitor NSC23766 under normoxia and hypoxia. Results:The mRNA and protein expressions of Rac1 and HIF-1α were upregulated in Eca109 cell line by hypoxia,up to the maximum in 24 h. Rac1 specific inhibitor NSC23766 reversed the hyoxia-induced upregulation of HIF-1α mRNA and significantly inhibited the proliferation of Eca109 cell line. Conclusion:Rac1 and HIF-1α were both activated by hypoxia,and might be involved in the proliferation of the cancer cell.