Chlamydia pneumoniae is detectable in the blood vessels of patients suffering from arteriosclerosis. Risk for arteriosclerosis is modulated by the apolipoprotein E (apoE) allele. We assessed the significance of the apoE genotype as a risk factor for vascular C. pneumoniae infection by determining the genotype of 30 coronary heart disease patients with PCR-proven C. pneumoniae infection of coronary artery tissue. The apoE genotype is not distinctly associated with an increased risk for vascular C. pneumoniae infection.