Cardiovascular disease (CAD) is the leading cause of death in developed countries. The cause is multifactorial. A
substantial proportion of patients with CAD do not have traditional risk factors. Infectious diseases may play a role
in these cases, or they may intensify the effect of the risk factors. The association of CAD and Chlamydia
pneumoniae infection is firmly established, but causality is yet to be proven. We investigated their presence in
carotid atherosclerotic plaques. 102 plaque atherosclerotic in dead patients were available for examination in
Tehran, Iran. The highly sensitive polymerase chain reaction method was employed with primers specific for this
agent. The presence of Chlamydia DNA was detected in 23 (22%) out of 102 examined samples. The presence of
Chlamydia DNA in these patients supports the hypothesis that this agent has an association with atherosclerosis.
