Introduction: Physical activity is considered to have influence on anthropometry and blood pressure. It is supposed that regular physical activity leads to better body composition and lowers blood pressure. The aimof the study: Evaluation of influence of regular physical activity offered by sports school on body composition and blood pressure in 14-year-old children. Material and methods: Twenty-five children from sports school participated in the study. Children were examined twice – interval was 12 months. Changes of anthropometric values, body composition and blood pressure values were analysed. Results: In whole group increase of systolic blood pressure was observed (p < 0.05), mainly in boys. Diastolic blood pressure didn’t change. Body composition changed negatively in whole group: fat mass increased (13% vs. 20%, p < 0.05), gain of fat mass was higher in girls (6% vs. 3%, p < 0.05). There was significant increase of BMI percentile in girls (37 vs. 49, p < 0.05), in boys this parameter didn’t change. Conclusion: Increased physical activity offered by sports school doesn’t improve nutritional status of 13–14-year-old girls and boys, whose body fat mass increase. School sport activity doesn’t reduce blood pressure in 13–14-year-old children, according to age standards. Centile values of boys systolic blood pressure were even higher.