To analyse eating and physical activity preferences among adolescent school children and to compare the teenagers' lifestyle declarations with their parents' beliefs. Unfavorable behavior in eating habits and physical activity may result in serious dysfunctions and diseases, such as eating disorders and incorrect body mass. A retrospective cross-sectional study conducted in 2010-2011. The data was collated from 711 pupils and 266 parents. The survey included questions on: breakfast consumption, types of food eaten for breakfast, time of supper, the daily number of meals, the quantity of fruit and vegetables, food products purchased in the school shop, as well as the type and level of physical activity. In the population of children aged 14-15 years, 10% do not eat 1st breakfast and 15% do not eat 2nd breakfast, 50% eat dairy products for 1st breakfast, 70% have sandwiches for 2nd breakfast, 45% most frequently buy snacks in the school shop, 65% prefer physical activity in the form of team games, and 90% willingly participate in PE classes. The parents' beliefs differ from their children's declarations with regard to: breakfast consumption, the number of meals a day, the quantity of fruit, and participation in PE classes. The lifestyle of the studied adolescents is within the norms recommended for their age group, although there is a tendency to skip breakfast. A positive aspect is the adolescents' engagement in physical activity. Parents underestimate their children's level of physical activity and overestimate their daily number of meals. The study confirms the validity of conducting health education, addressed to both children and their parents, with regard to correct eating habits and physical activity, as well as prevention of eating disorders. © 2012 Blackwell Publishing Ltd.