The Mediterranean diet is a healthy eating pattern with protective effects on chronic diseases. The purpose of this study was to assess the relation between BMI and obesity and the level of adherence to the traditional Mediterranean diet. The subjects were Spanish men (n = 1547) and women (n = 1615) aged 25-74 y who were examined in 1999-2000, in a population-based, cross-sectional survey in the northeast of Spain (Girona). Dietary intake was assessed using a FFQ. A Mediterranean diet score, including foods considered to be characteristic components of the traditional Mediterranean diet (vegetables, fruits, pulses, nuts, fish, meat, cereals, olive oil, and wine) was created. An increase of 5 U in the dietary score was associated with a change in the BMI of 0.43 (P = 0.030) and 0.68 (P = 0.007), after controlling for potential confounders, in men and women, respectively. The obesity risk decreased in men (P = 0.010) and women (P = 0.013) with increasing adherence to the traditional Mediterranean dietary pattern. The population in the top tertile of this score were less likely to be obese in both genders [odds ratio (OR) and (95% CI): 0.61 (0.40-0.92) in men; 0.61 (0.40-0.93) in women] after adjusting for potential confounders. These data suggest that the traditional Mediterranean dietary pattern is inversely associated with BMI and obesity. This finding may be useful in the development of dietary approaches for dietary counseling and the prevention of obesity.