The Mediterranean diet is receiving increasing attention in cardiovascular epidemiology. The association of adherence to the Mediterranean diet with the incidence of hypertension was evaluated among 9,408 men and women enrolled in a dynamic Spanish prospective cohort study during 1999-2005. Dietary intake was assessed at baseline with a validated semiquantitative food frequency questionnaire, and a 9-point Mediterranean diet score was constructed. During a median follow-up period of 4.2 years (range, 1.9-7.9), 501 incident cases of hypertension were identified. After adjustment for major hypertension risk factors and nutritional covariates, adherence to the Mediterranean diet was not associated with hypertension (the hazard ratio was 1.10 (95% confidence interval (CI): 0.81, 1.41) for moderate adherence and 1.12 (95% CI: 0.79, 1.60) for high adherence). However, it was associated with reduced changes in mean levels of systolic blood pressure (moderate adherence, -2.4 mm Hg (95% CI: -4.0, -0.8); high adherence, -3.1 mm Hg (95% CI: -5.4, -0.8)) and diastolic blood pressure (moderate adherence, -1.3 mm Hg (95% CI: -2.5, -0.1); high adherence, -1.9 mm Hg (95% CI: -3.6, -0.1)) after 6 years of follow-up. These results suggest that adhering to a Mediterranean-type diet could contribute to the prevention of age-related changes in blood pressure.