background: the importance of diet as a cause of different diseases and the possibility of educational involvement during the school-age years leads to it being advisable to ascertain the attitudes of young people with regard to nutrition and their eating habits. methods: cross-section study. a self-test survey was conducted regarding the nutrition-related habits and knowledge on a sample randomly taken from among 543 students from the 1st level school-leaving certificate studies (age 13) in the city of saragossa, including an assessment of the foods eaten by means of 24-hour recall and a questionnaire regarding how often different foods are eaten weekly. a pilot study was conducted on 50 individuals, with validation by means of personal interviews in 15 cases. results: a total of 516 questionnaires were analyzed. the subjects were found to possess an average degree of knowledge regarding nutrition-related matters. a total 41.5% of the sample acknowledged advertising having an impact on their diet. a greater diet-related impact was found to exist among the females analyzed. the eating survey revealed a diet consisting of normal calorie intakes, but excessive protein and low carbohydrate intakes, excess fat intake being noted among males. an excessive amount of meat and meat products and sweets and candies was noted, contrasting with the low grain, fish and potato intake. conclusions: educational measures must be taken among school-age children with regard to informing them concerning the composition of foods and a correct diet, teaching them to take a critical stance with regard to food advertising. they must be counseled to lessen their intakes of meats and sweets and to increase the amount of complex carbohydrates and fish.