Aim To investigate the changes and significance of expression of hypoxia inducible factor-1α(HIF-1α) in patients with coronary artery disease(CAD).Methods 120 patients with CAD,including 40 acute myocardial infarction(AMI),40 unstable angina pectoris(UAP),and 40 stable angina pectoris(SAP),were selected in this study,with 40 cases with normal coronary artery serving as controls.The mRNA and protein expression of HIF-1α in monocytes and lymphocytes isolated from subjects were examined by semi-quantitative reverse transcriptase polymerase chain reaction(RT-PCR) and Western blotting.Results There was no significant difference in HIF-1α mRNA expression between CAD patients and the controls.The protein expression of HIF-1α was significantly stronger in patients with CAD than in controls,and the expression levels increased with the severity of the disease.Conclusion HIF-1α protein may be useful marker to reveal severity of CAD.