This study is design to explore the association between dietary betaine intake and risk of all-cause and cardiovascular death in patients with CAD. In this cohort study, 1292 patients with CAD were followed-up for a median of 9.2 years. Baseline dietary betaine intake was collected using a paper-based semi-quantitative food frequency questionnaire (FFQ) and assessed according to the US Department of Agriculture (USDA) Database and the data of betaine in common foods. Cox proportional hazards regression models were used to analyze the association between dietary betaine intake and risks of all-cause and cardiovascular mortality. During the follow-up periods, 259 deaths recorded in 1292 participants, of which 167 died of cardiovascular diseases. Patients in the highest tertile of dietary betaine intake had a lower risk of all-cause (P=0.007) and cardiovascular death (P<0.001) than those in the lowest tertile after adjusting for age and sex, traditional cardiovascular risk factors and other potential confounders. After further adjusting for plasma methionine metabolites and vitamins, HRs across tertiles of dietary betaine intake were 1.00, 0.84 and 0.72 for all-cause mortality (P for trend=0.124), and 1.00, 0.77 and 0.55 for cardiovascular mortality (P for trend=0.021). Higher dietary betaine intake was associated with a decreased risk of cardiovascular death after fully adjustment for cardiovascular risk factors, other potential confounders and plasma methionine metabolites and vitamins. However, the association between dietary betaine intake and risk of all-cause mortality was not statistically significant after further adjusting for plasma methionine metabolites and vitamins.