RESUMEN
ADHD is the most common mental disorder in children. Awareness of students' mental health has an important role in programming for decrementing their disorders and, improving their mental health and also preventing the complications of their decreased mental health. The aim of this study was to determine the prevalence of ADHD and some of the affecting factors among school children in Nishaboor localed in the North-East of Iran. This descriptive study was done on school children in Nishaboor during 2006. Subjectes selected by stratified cluster sampling. Data collection was done using the Conner's Parent and Teacher Scale questionnaire, and each student's questionnaires were completed by both the teacher and the parents. Data analysis was performed regarding to the mean scores of teachers and parents. The score 15 was chosen as the probable indicator for ADHD. 722 students [79.6%] were involved this study. Prevalence of ADHD was 12.5%, CI95%: 10-14.8%. There was no significant difference in gender distribution. The prevalence of ADHD had a significant rise with age [P < 0.05]. The highest prevalence was in spring born and the lowest was in the summer born school children [P < 0.05]. The prevalence of ADHD had a significant relationship with father's education and was lower in students whose father had higher educations [P < 0.05]. Variables such as type of delivery, pariety, mother's education had no significant relationship with the prevalence of ADHD. In this study the prevalence of ADHD is higher than similar studies. Risk groups to be followed up by the responsible organizations