BACKGROUND AND OBJECTIVES: The Mediterranean diet has been demonstrated to provide a range of health benefits in observational and clinical trials and adopted by various dietary guidelines. However, a broad range of definitions exist impeding synthesis across trials. This review aims to provide a historical description of Mediterranean diets, from the ancient to the modern, to inform future educational and diet index tool development representing the 'traditional' Mediterranean diet. METHODS AND STUDY DESIGN: Nine databases were searched from inception to July 2015 to identify papers defining the Mediterranean diet. The definition accepted by the United Nations Educational, Scientific and Cultural Organization (UNESCO) was also reviewed. RESULTS: The 'traditional' Mediterranean diet is described as high in unprocessed plant foods (grains, vegetables, fruits, legumes, nuts/seeds and extra virgin olive oil), moderate in fish/shellfish and wine and low in meat, dairy, eggs, animal fats and discretionary foods. Additional elements relating to cuisine and eating habits identified in this review include frequent intake of home cooked meals; use of moist, lower temperature, cooking methods; eating main meals in company; reduced snacking occasions; fasting practice; ownership of a vegetable garden; use of traditional foods and combinations; and napping after the midday meal. CONCLUSIONS: Scope exists for future tools to incorporate additional elements of the 'traditional' Mediterranean diet to improve the quality, consistency, and synthesis of ongoing research on the Mediterranean diet.