The aim of this studywas to assess the validity and reproducibility of a self report questionnaire on sedentary behavior (Adolescent Sedentary Activity Questionnaire: ASAQ) among Brazilian adolescents. The sample consisted of 122 adolescents (62 females) aged between 12 and 17 years. ASAQ was developed and validated for adolescents in Australia (Hardy et al, 2007), and for its use in Brazil a transcultural adaptation to Portuguese was done, followed by an assessment of ASAQ’s contents by experts. Then, ASAQ was administered within schools, on a typical school day, followed by a retest administration four days later. Total sedentary time was calculated for weekdays and weekends. Total sedentary time was calculated for weekdays and weekends. Intra-class correlation coefficient (ICC) and confidence interval (CI95%) were calculated for both sexes. QASA (acronym for ASAQ Portuguese version) has 13 questions divided into five categories: screen recreation, educational, transportation, cultural activities, and social activities. ICC for total time spent on sedentary behavior was 0,88(CI95%=0.82-0.91) for weekdays, and 0,77 (CI95%= 0.68-0.84) for weekends. Between categories of sedentary behavior, ICC values varied from 0.75(CI95%=0.65-0.83) for transportation to 0.94 (CI95%=0.92-0.96) for screen recreation on weekdays, and from 0.40 (CI95%=0.15-0.58) for transportation to0.90 (CI95%=0.86-0.93) for screen recreation on weekends. In general, ASAQ hada satisfactory reproducibility for the assessment of sedentary behaviors among young people in Brazil.