There is evidence that a diet rich in fruit and vegetables reduces blood pressure (BP). Characteristically, the Mediterranean diet is rich in plant-derived foods and also in fat, but studies conducted in Mediterranean countries to relate diet to BP are scarce. We studied the association between fruit and vegetable consumption and BP in a cross-sectional analysis of 4393 participants in the Seguimiento Universidad de Navarra (SUN) Study, an ongoing dynamic cohort study in Spain. Diet was measured using a food-frequency questionnaire previously validated in Spain. Fat represented more than 37 % total energy intake. Subjects were considered to have undiagnosed hypertension if they reported systolic BP > or = 140 mmHg or diastolic BP > or = 90 mmHg, and not a medical diagnosis of hypertension. The adjusted prevalence odds ratio of undiagnosed hypertension (upper v. lowest quintile) was 0.58 (95 % CI 0.36, 0.91; P for trend 0.01) for vegetable consumption and 0.68 (95 % CI 0.43, 1.09; P for trend 0.10) for fruit consumption. Comparing those in the highest quintile of both fruit and vegetable consumption with those in the lowest quintile of both food groups, the prevalence odds ratio was 0.23 (95 % CI 0.10, 0.55; P = 0.001), after adjusting for risk factors for hypertension and other dietary exposures. In a Mediterranean population with an elevated fat consumption, a high fruit and vegetable intake is inversely associated with BP levels.