While several investigations have focused on the association between individual foods and nutrients upon the development of chronic diseases, few have examined the role that entire dietary patterns may play in health and disease. A dietary pattern generally considered to have beneficial health effects is that of the Mediterranean diet. In this paper, five cohort studies exploring the association of Mediterranean diet with overall mortality and hence longevity are reviewed. A number of conclusions can be drawn. First, there appears to exist sufficient evidence that diet does indeed influence longevity. Secondly, an optimal diet for the prevention of both coronary heart disease and cancer is likely to extensively overlap with the traditional Mediterranean diet. It is not yet clear which components in the Mediterranean diet are more important for its apparent health effects, but olive oil, plant foods and moderate wine consumption are likely candidates.