The aim of this work was to evaluate the repeatability and the validity of a food frequency questionnaire (FFQ), and to discuss the methodological framework of such procedures.The semi-quantitative FFQ included 69 questions regarding the frequency of consumption of all main food groups and beverages usually consumed and 7 questions regarding eating behaviors. Five hundred individuals (37 ± 15 yrs, 38% males) were recruited for the repeatability process, while another 432 (46 ± 16 yrs, 40% males) also completed 3-Day Diaries (3DD) for the validation process. The repeatability of the FFQ was adequate for all food items tested (Kendall's tau-b: 0.26-0.67, p < 0.05), energy and macronutrients intake (energy adjusted correlation coefficients ranged between 0.56-0.69, p < 0.05). Moderate validity of the FFQ was observed for "dairy products", "fruit", "alcohol" and "stimulants" (tau-b: 0.31-0.60, p < 0.05), whereas low agreement was shown for "starchy products", "legumes", "vegetables", "meat", "fish", "sweets", "eggs", "fats and oils" (tau-b < 0.30, p < 0.05). The FFQ was also valid regarding energy and macronutrients intake. Sensitivity analyses by sex and BMI category (< or ≥25 kg/m(2)) showed similar validity of the FFQ for all food groups (apart from "fats and oils" intake), as well as energy and nutrient intake.The proposed FFQ has proven repeatable and relatively valid for foods' intake, and could therefore be used for nutritional assessment purposes.