The present work to evaluate whether there is a significant relationship between atherosclerosis and Chlamydophila Pneumoniae (C. pneumoniae) infection by using the Enzyme Linked Immunosorbent Assay (ELISA) techniques to detect the antibodies, and polymerase chain reaction (PCR) to detect the microbial DNA. Case-control study was carried out on atheromatous plaque and serum samples obtained from 74 patients with peripheral arterial disease caused by atherosclerosis and another 14 patients with varicose veins as a control group in the Vascular Surgery Department, Sohag University Hospital over a period between October 2013 and June 2014. Chlamydophila pneumoniae DNA was extracted, amplified and detected using PCR assay, and anti - C. pneumoniae IgG antibodies were detected by ELISA assay. Both ELISA and PCR techniques were done for the studied cases and the control group. ELISA technique was positive for Chlamydophila pneumoniae IgG antibody in 40 patients (54.05%) among the studied cases while in the control group, it was positive only in 4 cases (28.57%) with p-value 0.08. PCR technique was positive in 28 patients (37.84%) in the cases for Chlamydia pneumoniae 16sRNA gene, while for the control group, all cases were negative with p- value 0.005. Conclusions: Chlamydophila pneumoniae infection can be considered as a strong risk factor for atherosclerosis.