BACKGROUND: No data exist regarding the effect of the Mediterranean diet on renal function. We studied the association between adherence to the Mediterranean diet and markers of renal function among 3042 people without any evidence of chronic disease. METHODS: During 2001 and 2002, a random sample was selected of 1514 men and 1528 women (aged 18 to 89 years) from Greece. Urea and creatinine were measured, and the creatinine-clearance (CCr) rate was estimated according to the formula of Cockcroft and Gault. Adherence to the Mediterranean diet was assessed using a validated diet score (MedDietScore) that incorporated the inherent characteristics of this diet. RESULTS: The CCr rate was positively associated with MedDietScore (b+/-SE, 0.24+/-0.09, P=.007). Moreover, urea and creatinine levels were inversely associated with MedDietScore (b+/-SE, -0.05+/-0.02, P=.01, and -0.004+/-0.001, P < .001, respectively). Multiple linear regression analysis revealed that for each 10/55 additional points in diet score, a 3.7-unit increase in CCr rate in women (P < .001) and a 10.1-unit increase in CCr rate in men were evident (P < .001). Further analysis revealed that the CCr rate was positively correlated with the consumption of fruits (rho =0.08, P=.009) and moderate alcohol consumption, and inversely correlated with the consumption of potatoes (rho=-0.11, P < .001), red meat (rho=-0.12, P=.001), and poultry (rho=-0.07, P=.02). CONCLUSIONS: Greater adherence to the Mediterranean diet was independently associated with reduced urea and creatinine and increased CCr rates among healthy men and women. This finding adds to the knowledge regarding the benefits of a traditional Mediterranean diet in human health.