The main goal of this thesis under the title “Differences in anthropometric characteristics between kids training tennis and the kids who are not engaged in organized sports” is to determine the differences in anthropometric characteristics and nutritional status between 15 kids who are not engaged in organized sports from Šegrt Hlapić kindergarten and 15 kids who are regularly training tennis from Tennis club Rally. In addition, the goal is also to determine whether there are significant differences between anthropometric characteristics and nutritional status between kids who are not engaged in organized sports and kids who are training tennis. For research purposes, body height and body weight of children who are not engaged in organized sports and children who are playing tennis are being measured considering that the children are aged 5 and 6 years old. Based on the obtained measurements, the BMI is calculated to determine the nutritional status of the children. The nutritional status of children is determined by certain graphical representations and based on this the results are compared between children who do not engage in organized sports and children playing tennis. The results of this study show significant differences in nutritional status between children who are not engaged in organized sports and kids who are training tennis. The results of this research show that as many as 40% of children who do not engage in organized sports showed results of obesity and overweight, while children who are playing tennis showed a minimal result of overweight and obesity of only about 7%. The obtained results demonstrate that engaging in physical activity has a positive effect on the nutritional status of children and on reducing the global problem of obesity in preschool children. In order to have a positive impact and to reduce the negative consequences on the nutritional status of children, it is necessary to encourage children to engage in physical activity from an early age. It is also important to regularly implement anthropometric measurements of children, and avoid on time any deviations in results, where educational institutions play a main role.