Greater adherence to the Mediterranean diet has been associated with a lower incidence of cardiovascular disease and cancer.We studied the effect of the Mediterranean diet on total antioxidant capacity (TAC) in 3042 participants who had no clinical evidence of cardiovascular disease.During 2001-2002, a random sample of 1514 men and 1528 women aged 18-89 y from the Attica area of Greece was selected. TAC was measured with an immune-diagnostic assay. Food consumption was evaluated with a validated food-frequency questionnaire, and adherence to the Mediterranean diet was assessed on the basis of a diet score that incorporated the inherent characteristics of this diet.TAC was positively correlated with diet score. The participants in the highest tertile of the diet score had, on average, 11% higher TAC levels than did the participants in the lowest tertile, even after adjustment for relevant confounders (P < 0.01). On the other hand, the participants in the highest tertile of the diet score had, on average, 19% lower oxidized LDL-cholesterol concentrations than did the participants in the lowest tertile (P < 0.01). An additional analysis showed that TAC was positively correlated with the consumption of olive oil (rho = 0.54, P = 0.002) and of fruit and vegetables (rho = 0.34 and rho = 0.31, respectively; P < 0.001 for both), whereas it was inversely associated with the consumption of red meat (rho = -0.35, P = 0.02).Greater adherence to the Mediterranean diet is associated with elevated TAC levels and low oxidized LDL-cholesterol concentrations, which may explain the beneficial role of this diet on the cardiovascular system.