Being the most common cause of death from poisoning worldwide, cardiovascular manifestations of acute carbon monoxide (CO) poisoning have been subject of various studies but current evidence about effects of chronic CO exposure on atherosclerosis is limited which is very common. We aimed to investigate association of chronic CO exposure with atherosclerosis by measuring carotid intima-media thickness (CIMT) and high-sensitivity C-reactive protein (hs-CRP). Forty healthy male non-smoker indoor barbecue workers (mean age; 33.0 ± 9.0 years) working in different restaurants for at least three years and 48 age-matched healthy men (mean age; 34.3 ± 6.6 years) enrolled in the study. Clinical characteristics of indoor barbecue workers and control group were comparable in terms of body mass index, blood pressure, and lipid profile. However, carboxyhemoglobin (COHb) (6.4 ± 1.5% vs. 2.0 ± 1.1%), hs-CRP (2.7 ± 2.0 mg/L vs. 1.1 ± 0.8 mg/L) and CIMT (1.1 ± 0.3 mm vs. 0.9 ± 0.1 mm) were higher in indoor barbecue workers (p < 0.001 for each). In Pearson correlation analysis, CIMT was correlated with COHb concentration (r = 0.635, p < 0.001) and hs-CRP level (r = 0.466, p < 0.001). Among indoor barbecue workers, the years worked (years exposed to CO) are correlated with COHb, hs-CRP and CIMT. In multivariate analysis, COHb concentration is the only independent predictor of CIMT (β = 0.571, p < 0.001). The increased CIMT and hs-CRP in indoor barbecue workers suggest that chronic CO exposure may increase the risk of atherosclerotic cardiovascular events.