BACKGROUND: Although adherence to the Mediterranean diet has long been associated with lower incidence of various chronic diseases among apparently healthy individuals, its relationship with the severity and short prognosis (30 d) of patients with cardiovascular disease has rarely been investigated. OBJECTIVE: We sought to evaluate the association between adherence to the Mediterranean diet and the severity and prognosis of acute coronary syndromes. METHODS: From October 2003 to September 2004, a sample of 6 hospitals located in several urban and rural Greek regions was selected, and almost all survivors after an acute coronary syndrome were enrolled into the study (2172 patients were included in the study; 76% were men and 24% women). Adherence to the Mediterranean diet was assessed by a diet score that incorporated the inherent characteristics of this diet. Higher values of the score (range 0-55) were closer to the Mediterranean diet. Biochemical indices of myocardial damage were also considered. RESULTS: Diet score was inversely correlated with entry values of cardiac troponin I (rho = -0.19, P < 0.001), creatine phosphokinase (rho = -0.09, P < 0.001), and creatine phosphokinase-MB (rho = -0.09, P < 0.001). An increment in the diet score was associated with significant decrease in troponin I and creatine phosphokinase-MB levels (P < 0.01) after adjusting for various potential confounders. Moreover, diet score was associated with lower risk of recurrent events (odds ratio = 0.81, 95% confidence interval 0.61-0.98). However, this association became insignificant when the discharge diagnosis of the patients was taken into account. CONCLUSION: Background dietary habits close to the Mediterranean diet seem to be associated with lower severity of coronary heart disease.