Since Saikku's investigations in 1988 a direct relation between atherosclerosis and infection with Chlamydia pneumoniae has been suspected. The aim of the present study was to examine histologically normal and atherosclerotic femoral arteries of autopsy cases and to correlate histological findings with the presence of Chlamydia pneumoniae which was tested with nested polymerase chain reaction. The study included all of the femoral arteries (of which 16 male, 15 female, aged between 50 and 88 years) obtained by autopsy from the cases occurring between July 1, 1999 and August 31, 1999 in the Medical Clinic Darmstadt. Each paraffin block supplied us with six consecutive sections of which the first two sectional areas were histologically stained, while the other four were used in PCR examination for DNA extraction. The polymerase chain reaction did not reveal presence of Chlamydia pneumoniae in any of the cases, neither in atherosclerotic lesions, nor in normal arteries. Because of the negative results, an additional PCR test was performed with primers that amplify another region of the Chlamydia genome, but the result did not change. The negative result of our prospective study does not contradict the assumption that infection with Chlamydia pneumoniae may enhance the progress of atherosclerosis in single cases. However, the results do not favour the concept of atherosclerosis as an infectious disorder caused by Chlamydia pneumoniae.