Background: Excessive increases in percentage body fat (%BF) according to sex may pose greater risks of chronic diseases. Objective: To evaluate trends of body composition according to sexual maturation stage and body mass index (BMI) of adolescents. Method: Data about weight, height, lean mass, fat mass, %BF, BMI and sexual maturation of 1345 private school students (685 girls) aged from 7 to 18 years were collected in 2001 and compared with data of 1450 students (750 girls) collected in 2010 in Campinas, Brazil. chi(2)-test, ANOVA and logistic regression were used for statistical analyses (p<0.05). Results: Obesity prevalence increased, and number of boys and girls with normal BMI (p=0.0183 and p=0.0041) decreased. Differences in the median values of the study variables according to time point and nutritional diagnosis were not significant, except for lean mass (p=0.0484) and height (p=0.0275) in B2 (Breast stage) and %BF (p=0.0324) in G5 (Genitalia stage). Conclusion: Body composition did not change significantly, although overweight increased.o TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.2641858651656Rectory of Pontificia Universidade Catolica de Campinas (PUC Campinas) from its Undergraduate Research Fund (FAPIC/Reitoria)