Aim To evaluate expression levels of the 5 kinds of antimicrobial peptide genes,cathelicidin(CAMP)and alpha-defensin 1-4(DEFA1-4)in peripheral blood mononuclear cells(PBMC).Methods Sixty-one patients with coronary artery disease(CAD)who had stable effort angina pectoris and had ≥50% diameter stenosis in left main coronary artery or at least one major coronary artery were involved in this study.Controls(n=53)were those with chest pain,abnormal ecletronic cadiogram or abnormal echocardiography,but had a smooth coronary angiogram(CAG).Venous blood was obtained before CAG for RNA isolation and routine blood count.Ten μg/patient of the total RNA were used for individual cDNA preparation.Expression levels of genes in individuals were evaluated by quantitative real-time RT-PCR.Results WBC count and subset counts were not different between CAD and control group,except that relative lymphocyte count in percentage was lower in the former than that in the later(27.2%±1.2% vs 31.7%±1.5%,P>=0.02).Level of CAMP gene expression was higher in CAD than that in the control [1.21(0.98～1.55)vs 0.97(0.69～1.39),P>=0.009)].Expression levels of DEFA 1-3 genes were elevated in CAD than that in the control[0.85(0.58～1.21)vs 0.61(0.41～0.86),P>=0.003)].CAD group also presented higher expression level of DEFA 4 gene than the control group [0.78(0.52～1.43)vs 0.47(0.32～0.74),P>=0.001)].The differences of these gene expression levels were not due to variations of WBC subset counts as judged by correlational analysis(all P>0.05).CAD patients had higher hs-CRP level than the controls [2.0(1.0～4.0)mg/L vs 1.0(0.5～2.4)mg/L,P>=0.02)].Expression levels of DEFA1-3,DEFA4,CAMP were not correlated with CRP level.Conclusion Expression levels of antimicrobial peptides,alpha-defensins and cathelicidin in PBMC,may be associated with coronary artery atherosclerosis.