AIM: To determine the overall prevalence of H pylori and CagA positive H pylori infection and the prevalence of other bacterial and viral causes of chronic infection in patients with coronary heart disease (CHD), and the potential role of anti-heat-shock protein 60 (Hsp60) antibody response to these proteins in increasing the risk of CHD development.METHODS: Eighty patients with CHD and 160 controls were employed. We also compared the levels of antiheat-shock protein 60 (Hsp60) antibodies in the two groups. The H pylori infection and the CagA status were determined serologically, using commercially available enzyme-linked immunosorbent assays (ELISA), and a Western blotting method developed in our laboratory.Systemic antibodies to Hsp60 were determined by a sandwich ELISA, using a polyclonal antibody to Hsp60 to sensitise polystyrene plates and a commercially available human Hsp60 as an antigen.RESULTS: The overall prevalence of H pylori infection was 78.7% (n = 63) in patients and 76.2% (n =122) in controls (P = 0.07). Patients infected by CagApositive (CagA+) H pylori strains were 71.4% (n = 45) vs 52.4% of infected controls (P = 0.030, OR = 2.27). Systemic levels of IgG to Hsp60 were increased in H pylorinegative patients compared with uninfected controls (P＜ 0.001) and CagA-positive infected patients compared with CagA-positive infected controls (P = 0.007).CONCLUSION: CagA positive H pylori infection may concur to the development of CHD; high levels of antiHsp60 antibodies may constitute a marker and/or a concomitant pathogenic factor of the disease.