Objective: To assess hyperactivity (H/I), inattention (IN), and oppositional-defiant (OP) symptoms in a nonclinical Brazilian sample of adolescents, and to investigate the association between scoring profiles of teachers and parents, symptom levels, and gender. Method: Symptoms were assessed through the Swanson, Nolan, and Pelhman (SNAP-IV) Questionnaires distributed for teachers and parents to fill out. Score means and prevalence rates based on Criterion A of the "Diagnostic and Statistical Manual of Mental Disorders" (4th ed.) for ADHD or oppositional-defiant disorder were estimated. Agreement rates between teachers and parents were calculated for each group of symptoms. Mean scores were compared by gender. Results: Between 7% and 33% of students were rated as having high scores of symptoms. Boys and girls had the same level of symptoms, when scored by parents. Teachers rated boys as having more H/I and OP symptoms. Parents gave scores significantly higher for H/I and OP symptoms, and teachers rated more students as inattentive. Conclusions: H/I, IN, and OP symptoms were highly prevalent in this nonclinical sample. Few differences between boys and girls were observed in symptom levels. Teachers and parents have different scoring profiles for the different SNAP subscales and are probably influenced by cultural aspects. (Contains 3 tables.)