We investigated the presence of Chlamydophila pneumoniae antibodies in 125 patients with cardiovascular disease and in 128 controls. C. pneumoniae antibodies were measured by microimmunofluorescence assay. A significantly high prevalence of IgG C. pneumoniae antibodies at titre > or = 8 was found in patients (84%) in comparison to controls (47.6%). Considering as cut-off the IgG titre > or = 32, 52% of patients with coronaropathies and 18.75% of controls resulted positive (p < 0.0001). IgA C. pneumoniae antibodies were found in patients and controls without statistically significant differences. High C. pneumoniae antibodies (titre > or = 256) were found in 11% of patients with acute myocardial infarction (AMI) and in none of the controls. In patients, the percentage of IgG and IgA seropositivity increased with age and decreased in patients aged > 70 years. Only patients with AMI are at risk of having antibodies against C. pneumoniae (OR = 6.69). None of the known risk factors for cardiovascular disease was significantly associated with C. pneumoniae seropositivity IgG. This is the first report in our area on the possible association of C. pneumoniae IgG seropositivity and acute ischemic events.