The aim of the present study was to assess the prevalence of the Mediterranean dietary pattern (MDP) in the population of the Balearic Islands and socio-demographic and lifestyle factors that might determine adherence to the MDP. A cross-sectional nutritional survey was carried out in the Balearic Islands between 1999 and 2000. A random sample (n 1200) of the adult population (16–65 years) was interviewed. Dietary questionnaires incorporating questions related to socio-economic status, education level, lifestyle factors and health status were utilised. Dietary habits were assessed by means of two 24 h recalls, and a quantitative food-frequency questionnaire. Adherence to the MDP was defined according to a score constructed considering the consumption of nine MDP characteristic components: high MUFA:saturated fatty acids ratio, moderate ethanol consumption, high legumes, cereals and roots, fruits, vegetables, and fish consumption, and low consumption of meat and milk. Then, socio-demographic, lifestyle and health status variables that could determine a higher or lower adherence were assessed. Adherence to the MDP among the population of the Balearic Islands was found to be 43·1 (sd 5·8) %, and was similar in all socio-demographic and lifestyle groups, with some differences according to age, sex and physical status. There was an increase in the percentage of adherence with age, which was greater in males than in females. A more physically active lifestyle was associated with a higher adherence to the MDP. The promotion of the Mediterranean lifestyle, including the MDP and greater physical activity, should be reinforced in the population of the Balearic Islands and especially in the younger generations.