The prevalence of the hyperactive-attention deficit symptomatology was studied using two common criteria in the research on and clinical practice in the Attention Deficit Hyperactivity Disorder (ADHD): the diagnostic criteria of the DSM-IV-TR (APA, 2000) and the clinical criterion established for the scale ADHD Rating Scale-IV (DuPaul, Power, Anastopoulos, & Reid, 1998). The studied sample comprised 500 subjects with ages between 10 and 16 years. The results, considering the distribution of the subtypes of the TDAH, show a global percentage clinical level of 4.8% (1.2% combined subtype, 2% hyperactive subtype and 1.6% attention deficit subtype), as opposed to 23 % that offers the screening by means of diagnostic criteria (4.4 % combined subtype, 2.6 % hyperactive subtype and 16.8 % unattentive subtype). Such results reveal important discrepancies among both systems of classification, particularly regarding the attention deficit subtype. There is a final discussion on the adjustment of current diagnostic criteria like screening for the detection of students with ADHD.