Aim: To evaluate the validity of body mass index (BMI) and bioelectric impedance analysis (BIA) methods in determining body compositions in healthy male and female adolescenses.

Materials and Methods: Body composition of 665 (359 male and 306 female) students, aged between 14-16 (mean±SD: 15.1±0.6 yr) were analysed using BMI and BIA methods.

Results: Normal ranges for BMI (18.5-24.99 kg/m²) in male students for the ages 14, 15 and 16 years found to be: 51.02% (n=25), 65.46% (n=127) and 70.68% (n=82) respectively. However, normal values for body fat mass percents for the ages 14, 15 and 16 years were 22.44% (n=11), 19.94% (n=29) and 13.79% (n=16). In female students, normal ranges for BMI found to be %52.00 (n=26), %68.44 (n=141) and % 68.00 (n=34). However, normal values for body fat mass percents for the ages 14, 15 and 16 years were 28.00% (n=14), 34.46% (n=71) and 22.00% (n=11).

Conclusion: In adolescense, BMI values may be insufficient method to analysis body composition. Thus BIA method should be considered to determine body composition especially in clinical evaluation.