There is substantial evidence that several variants of the Mediterranean diet reduce the incidence of coronary heart disease (CHD) and perhaps other chronic conditions. Recently, the final results of the Lyon Diet Heart Study, a randomized secondary prevention trial, indicated that the Mediterranean diet substantially reduces the rate of recurrence after a first myocardial infarction. Data from this study also suggest that the Mediterranean diet protects against CHD through mechanisms that are independent of traditional CHD risk factors. We postulate that the antioxidant properties of several plant foods in the Mediterranean diet may be critical mediators of the beneficial effects of this diet.