Background: Homocysteine is an independent risk factor for atherosclerosis, plausibly through induction of endothelial dysfunction and smooth muscle cell proliferation. Under oxidative stress and inflammatory stimuli, vascular smooth muscle cells may undergo osteogenic differentiation, which leads to coronary artery calcification. This study evaluated the association between plasma homocysteine and coronary artery calcification. Design and methods: Coronary artery calcium scores (CACSs) and plasma homocysteine concentrations were measured in 21,235 men (42 +/- 6.5 years) who participated in the Kangbuk Samsung Health Study between 2010 and 2011. Subjects were grouped by quartile of plasma homocysteine. Results: The prevalence of coronary artery calcification (CAC) among the 21,235 men was 13.5%. In the first to fourth homocysteine quartiles, CAC(+) prevalence rates were 12.1%, 12.6%, 13.9%, and 15.3%, respectively. The CAC(+) group had unfavorable cardiometabolic and lipid profiles. In multivariate regression analysis after adjusting for variables with a univariate relationship (p < 0.20), the odds ratio (OR) for the presence of CAC was higher for the highest homocysteine quartile than for the lowest quartile group (OR (95% confidence interval (CI)), 1.275 (1.027, 1.583)), and presence of CAC was positively associated with quartile of homocysteine (p for trend = 0.009). Moreover, absolute plasma homocysteine concentration was positively and significantly related to presence of CAC and to CACS, respectively (OR (95% CI) 1.399 (1.089, 1.796): standardized beta = 0.040, p < 0.001). Conclusions: This study shows that plasma homocysteine is independently related to coronary artery calcification in Korean men, suggesting that plasma homocysteine concentration may serve as a marker for CAC.