Proper eating habits and physical activity are important part of healthy lifestyle, therefore they should be adopted in younger age. This study aims to determine representation of physical activity and assesment of eating habits of the school age children regarding their age and therefore suggest proper health improvement measures of the school age children. The instrument of the study was questionnaire specifically designed for the research purposes, predicted for AutoFill. Retrospective cross sectional study was carried out on the sample of 150 respondents divided in three groups based on their school age, of which 82 (54,7%) were girls and 68 (45,3%) were boys. Number of students actively involved in sport significantly decreases with older school age (p=0,0001). Furthermore, time spent in walk or bicycle riding is also decreasing with older school age (p=0,006). On the contrary, time spent in front of a TV or computer is significantly increasing with age (p=0,0001). There is obvious problem of overweight and obese children and adolescents, affected more than 1/5 of the 3rd grade High school children. Educational and health institutions should be more engaged in resolving this problems, in order to promote health and prevent later diseases and/or complications.