BACKGROUND Although there is enough evidence that infectious agents such as Chlamydia pneumonia and Helicobacter pylori may play a pathogenic role in atherosclerosis, this role for cytomegalovirus (CMV) is yet controversial. OBJECTIVE The aim of the present study was to detect CMV-DNA in atherosclerotic plaques in patients who underwent coronary artery bypass graft (CABG). METHODS In this case-control study, candidates for CABG (cases) and patients with valvular or congenital malformation but without atherosclerotic plaques (controls) were studied from 2012 to 2013 at Golestan hospital, Ahvaz, IR Iran. Demographic and laboratory data were collected. Atherosclerotic and histological samples were obtained from visible plaques and from aorta by the surgeon. All the samples were examined for the presence of CMV-DNA by polymerase chain reaction (PCR) method using a commercial kit (SinaClon, Tehran, IR Iran). RESULTS The mean ages in case and control groups were 60.8 ± 6.8 and 57.5 ± 11.5 years, respectively, with no significant difference (P = 0.09). Thirty patients (54.5%) in case and 32 (58.2%) in control groups were male with no significant difference (P = 0.7). CMV-DNA was present in 8 (14.5%) of the cases and 2 (4%) of the controls. CMV-DNA was associated with higher risk of atherosclerosis (OR: 7.7, 95% CI = 1.1-51.4, P = 0.03). Of the total normal aortic samples (55 in cases and 55 in controls), there was no individual with simultaneous positive CMV-DNA among aortic atherosclerotic and normal tissue samples. CONCLUSIONS The presence of CMV-DNA in aortic plaques is associated with increased risk of atherosclerosis. CMV infection may be considered as an independent risk factor for this event.