Abdominal obesity is a strong predictor of metabolic disorders. Prospective data on the association between the Mediterranean diet and surrogate markers of abdominal adiposity are scarce. The present study evaluated the relationship between adherence to the Mediterranean diet and (1) changes in waist circumference (WC) and (2) 10-year incidence of abdominal obesity. We conducted a prospective, population-based study in 3058 male and female Spaniards aged 25–74 years, followed from 2000 to 2009. Dietary intake and leisure-time physical activity levels were recorded using validated questionnaires. Weight, height and WC were measured. Adherence to the Mediterranean diet, determined using the previously validated REGICOR-Mediterranean diet score (R-MDS), based on the distribution of population food intake and on the dietary recommendations (MDS-rec), was negatively associated with WC gain (P= 0·007 and 0·024, respectively) in fully adjusted models. In the multivariate logistic analysis, the odds of abdominal obesity incidence decreased across the tertiles of the R-MDS, but the association was not significant. In conclusion, adherence to the Mediterranean diet was associated with lower abdominal fat gain, but not with 10-year incidence of abdominal obesity.