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Background & objectives: Considering the importance of prevalence studies in disease management, this study was conducted to determine the prevalence of psychiatric disorders in children and adolescents in Ardabil province.
Methods: In this study, 1035 children and adolescents aged 6 to 18 were selected using cluster random sampling and examined with a digital version of the K-SADS in terms of psychiatric disorders. In the present work, 24 types of psychiatric disorders in children and adolescents were evaluated.  Sampling was done in the general population and interviews were conducted at the door of the house. Assessments were carried out by experienced psychologists. The point and interval prevalence (with 95% confidence interval) were calculated for disorders. Data were analyzed using SPSS ( v.22) software. 
Results: Hyperactivity, oppositional defiant, enuresis, and separation anxiety disorders had the highest prevalence in the studied sample. In contrast, psychosis, autism and panic disorders had the lowest prevalence. Depression had a moderate prevalence (1.7%) among other disorders. The overall prevalence of disturbances was 31.7%.
Conclusion: The prevalence of psychiatric disorders in Ardabil children and adolescents was high. According to this rate, etiologic studies are necessarily needed  for disorders  with  have high prevalence and health systems should design and manage  preventive plans for the general public.