Attention-deficit hyperactivity disorder (ADHD) is a common childhood condition, recognized as an important social-medical problem. The syndrome is characterized by motor system, perception, cognition and behavioral disturbances, compromising the learning of children with adequate intellectual potential. To investigate its prevalence in first grade pupils 484 children with DSM-IV diagnostic criteria and neuropsychological criteria were examined. The prevalence of ADHD was 18% when the diagnosis was made using DSM-IV criteria; 3.5% when neuropsychological criteria was used, including, in addition to behavioral and psychometric aspects, a discrepancy in the evolutionary neurological examination, and 3.9% when motor persistence was taken into account. The prevalence of ADHD was higher among older children (92.4 months) only when DSM-IV criteria were used. We conclude that the use of DSM-IV criteria probably overestimates the prevalence of ADHD, since it detects another behavioral disorders. In this context, they may be useful as screening, since they have adequate pre-testing performance.