Attention Deficit Hyperactivity Disorder (ADHD) is the most common neurobehavioural disorder among schoolchildren. Having information about extent of ADHD and its predisposing factors is essential in psychological services improvement and preventive measure development. the aim of this study was to determine the prevalence of ADHD and its related epidemiologic factors among school age children.

This cross- sectional study was accomplished in 2007 using a representative randomized multistage sampling method of primary school children. Data collection was carried out by using questionnaire included demographic characteristics and CSI-4 (Child Symptom Inventories Manual). Students were evaluated by using CSI-4 (which part in related to diagnose ADHD included an 18-item teacher and 18-item parents rating questionnaire) which included all 18 DSM-IV ADHDdiagnostic criteria. Then the collected data was analyzed by using χ2 statistical test. P-value< 0.05 was considered significant.

According to the results, Participants included 58 children with ADHD (40 boys, 18 girls). Most of them were studying in public schools (72.7%) and living in two-parent families (94.5%). the prevalent of ADHD prevalent among primary student in Gorgan was 13.68% overall, 68.97% in boys and 31.03% in girls (the ratio was 2.22 / 1). the prevalence of inattentive subtype was 31.37% and prevalence of hyperactivity subtype was 24.53%. There was significant relation between ADHD and gender, the rank of birth, parents' education and job (P < 0.05).

Because of higher prevalence of ADHD in this study than others, it seems development of etiological investigation and educational - counseling programs to be necessary.