Objective: To screen for Attention Deficit Hyperactivity Disorder (ADHD) diagnosis in children with academic underachievement (AU), by applying the Swanson, Nolan, and Pelham (SNAP-IV) questionnaire, furthermore to identify associated epidemiologic factors. Methods: A cross-sectional observational and epidemiological study, conducted through the medical records and their respective score in the SNAP-IV questionnaire of school-aged children, evaluated at academic underachievement outpatient clinic of a university hospital. The analyzed variables were SNAP-IV score, gender, Body Mass Index (BMI), grade and age. Results: of the 56 participants, 36 (66.1%) were male, the mean age was 8.7 years, and most were in the 3rd and 4th grades. About 38 (67.9%) of the subjects had positive score for ADHD diagnosis, being 28 (50.0%) boys and 10 (17.9%) girls, with a ratio of 2.8 boys:1 girl. There was association between inattention and obese children, which had higher inattention levels (p = 0.0362). There wasn’t association among another variables. Conclusion: The SNAP-IV questionnaire is an effective tool for screening of symptoms of inattention, hyperactivity and impulsivity. There was association between inattention and obesity.