Aim To explore the relation between serum levels of C-reactive protein(CRP) and soluble intercellular adhesion molecule-1(sICAM-1) and Chlamydia pneumoniae(Cpn) infection and coronary heart disease(CHD).Methods Serum levels of CRP,sICAM-1 and IgG,IgM antibodies to Cpn were detected by enzyme-lined immunosorbent assay(ELISA) in 60 patients with CHD and 40 healthy subjects.These patients were divided into four groups:acute myocardial infarction(AMI),unstable angina pectoris(UAP),old myocardial infarction(OMI) and stable angina pectoris(SAP).Results Cpn-IgG positive rates and levels in patients with CHD were significantly elevated compared with control group(p<0.01);Cpn-IgG positive rates between each group weren't different significantly(p>0.05);Cpn-IgG levels in AMI were higher than in OMI,UAP and SAP(p<0.05);Cpn-IgM positive rates in patients with CHD weren't different compared with control group(p>0.05).The levels of CRP and sICAM-1 in patients with CHD were significantly elevated compared with control group(p<0.01);the levels of CRP and sICAM-1 in AMI were significantly higher than in UAP,OMI and SAP(p<0.01);The levels of CRP and sICAM-1 in UAP were higher than in SAP.There was correlation between the levels of CRP,sICAM-1 and Cpn-IgG in patients with CHD(p<0.05).Conclusion The levels of CRP and sICAM-1 may reflect the severity of CHD at some degree.There is correlation between Chlamydia pneumoniae infection and CHD.Both inflammation and infection are revelant to CHD.