The aim of this study was to determine the relationship between body mass index (BMI) and body fat percentage (% BF) among 1000 healthy adolescents (ages, 15-19 y) from different areas in Serbian Republic (Federation of Bosnia and Herzegovina), during 2014. In this study examined adolescents were divided into four groups after calculating BMI, and after the correlation between BMI and %BF. The obtained results show that there are significantly more (p < 0.01; p < 0.05) boys (ages, 15-18) with a healthy weight than girls. The correlation between BMI) and %BF was very strong, positive, among examined girls (r = 0.975) and boys (r = 0.752). In a group with normal % BF and increased BMI there were significantly more (p < 0.01) boys than girls, and the opposite situation were in a group with increased BMI and % BF, where it was significantly more (p < 0.05) girls than boys. Obtained results show that the majority of adolescents in the Serbian Republic have normal body weight, with a tendency of increase, especially among girls who are more prone to unbalanced nutrition.