Background: Anti- Helicobacter pylori (HP) IgA and IgG antibody titers were measured in patients with ischemic heart diseases. Methods: There were 60 healthy individuals that served as control subjects, and 21 patients with acute myocardial infarction (AMI), 34 with old myocardial infarctions (OMI), 35 with effort angina (AP) and 41 with vasospastic angina (VSA). Results: In the control group, the IgA and IgG anti-HP antibody titers were positively correlated with age. When the IgA and IgG antibody titers were compared among patient groups, IgG did not significantly differ between each patient group and the control group, whereas IgA was significantly higher in the AMI group (5.10±1.25 EV) than in the OMI ( p<0.01), AP, or the control ( p<0.05). Moreover, the positivity rate for IgA anti-HP antibody was the highest in the AMI group (90%), with an odds ratio to the age-matched control group of 4.09, whereas the positivity rate for IgG did not significantly differ between the groups when either the 10 or 55 U/ml cut-off value was used. Conclusions: These results suggest that an increased IgA antibody titer, which is an index of the active phase of HP infection, should be an etiological marker for acute myocardial infarction.