PURPOSE: The Mediterranean diet has been postulated as a protective factor against different diseases including stroke. Thus, an epidemiological study in a Mediterranean country, such as Spain, focused on diet may offer new insights of the potential benefits of this nutritional pattern to prevent the onset of cerebrovascular diseases. METHODS: The SUN ("Seguimiento Universidad de Navarra") project is a prospective study among Spanish university alumni, aimed to identify the dietary determinants of stroke, coronary disease and other disorders. Two pilot studies have been developed. The first pilot study was focused on the understanding of the questionnaire. The second study used a random sample to assess the response proportion and the feasibility of using a mailing system for following-up the cohort. The first informative results are expected to be available after the first four years of following-up the cohort (2005). Here, we report the description of the baseline diet of the first participants in the cohort using data from 1,587 men and 2,260 women. RESULTS: The outcome of our pilot studies ensure the feasibility of a mail-based cohort. In the baseline assessment, we found a high consumption of olive oil (18.5 g/person/day), red wine (28.8 g/person/day), legumes (102.5 g/person/day), vegetables (507.8 g/person/ day) and fruits (316.7 g/person/day), with a great between-subject variability. Also, the values for cereals (170.4g/person/day), dairy products (239.3 g/person/day) and meat and meat products consumption (186 g/person/ day) in this cohort were estimated. The coefficients of variation ranged in women from 56 (for vegetables) to 240% (for red wine) and in men from 62 to 180% (for these same two items), reflecting a wide heterogeneity in the diet of participants. CONCLUSIONS: Although the participation was not high (22% according to the estimates of the pilot study), it was comparable to the proportion found in large previous cohorts such as the Nurses-II Health Study (24%). The sharp contrast in dietary habits between the US and Spain together with the high between-subjects variability we have found in our Spanish cohort provides an exceptional opportunity to assess the aspects of the Mediterranean diet, which may be protective against stroke and other neurological disorders.