Atherosclerosis, a common cause of atherosclerotic vascular diseases, is associated with several risk factors including hyperhomocysteinemia, and vitamin B 12 and folate are involved in homocysteine metabolism; thus, serum folate and vitamin B 12 status may be associated with the risk of atherosclerotic vascular diseases mediated by homocysteine plasma concentrations. Therefore, we hypothesized that low vitamin B 12 and folate levels are related to higher risks of atherosclerotic vascular disease and investigated the risk of atherosclerotic vascular events in Korean adults with low serum vitamin B 12 and folate levels. This population-based cohort study followed 421 subjects aged 40-69 years for 12 years, 2003-2014. Over the follow-up period, 38 (9.0%) atherosclerotic events occurred. However, serum folate and vitamin B 12 levels were not associated with the risk of stroke, coronary artery disease, or myocardial infarction or the development of peripheral arterial disease after adjustment for age, sex, smoking status, alcohol consumption, physical activity, body mass index, serum creatinine, and high-sensitivity C-reactive protein levels and a history of diabetes, hypertension, or dyslipidemia. In conclusion, the incidence of atherosclerotic vascular events in Korean adults aged 40-69 years was not associated with the serum folate or vitamin B 12 status.