Myocardial Infraction (MI) is one of the most causes of morbidity and mortality in industrial and developing countries. Recent studies have suggested that chronic infections with Chlamydia pneumoniae (Cpn) and Helicobacter pylori (Hp) may be associated with the risk of coronary heart disease (CHD). Determining risk factor of the CHD is of huge significance, so we executed the comparative study of antibody level to Chlamydia pneumoniae and Helicobacter pylori in patients with MI and healthy control in North of Iran. A cross sectional study was conducted on 140 citizens includes 70 cases and 70 controls that matched in age and sex. Seroprevalence was assessed by commercial ELISA tests measuring IgA and IgG antibodies to Cpn and Hp in sera. In this study, our results indicated that among patients, %11.4 was seropositive for Anti-Cpn IgA, %90.0 was seropositive for Anti-Cpn IgG, %51.4 was seropositive for Anti-Hp IgA and %58.6 was seropositive for Anti-Hp IgG. The present study shows that %68.57 of patients and %69.86 of controls are seropositive for anti-Hp specific IgA and IgG antibodies. Our findings show that previous infection to Cpn in patients with MI is important. But there are no significant association between infection with Hp as evidenced by elevated antibodies to Hp and MI.