Recent studies have associated evidence of Chlamydia pneumoniae infection with coronary and carotid atherosclerosis and evidence of increased infection with cytomegalovirus (CMV) in patients developing restenosis or with atherosclerosis. Several other common pathogens have been less consistently associated with atherosclerosis. Altered parameters of inflammation and hemostasis have been identified as prognostic factors of myocardial infarction and have been linked as possible pathogenetic mechanisms. Recent studies have indicated that peripheral blood mononuclear cells (PBMC) from patients with coronary artery disease frequently include Chlamydia pneumoniae DNA and stimulation of PBMCs can reflect an unsuccessful host cellular immune response to CMV associated with elevated C-reactive protein (CRP).