Objective: The objective was to examine the frequency of comorbid disorders in children and adolescents with ADHD in Turkey and to evaluate the distribution of comorbidities according to the subtypes of ADHD and sociodemographic features. Method: The sample consisted of 1,000 children, 6 to 18 years of age, including 242 females and 758 males, from Ege University who were diagnosed with ADHD. Results: The overall prevalence rate of psychiatric comorbidity in the study was 56.3%. The most frequently observed comorbidity was oppositional defiant disorder with a rate of 37.4%. Conduct disorder, depressive disorder, obsessive-compulsive disorder, and anxiety disorder accompanied ADHD, respectively. The results revealed that 70.2% of the children with ADHD-Combine type had at least one psychiatric comorbidity. Oppositional defiant disorder, conduct disorder, depressive disorder, and obsessive-compulsive disorder accompanied ADHD-Combine type in 54.6%, 12.6%, 8.1%, and 8.8% of the participants, respectively. Conclusion: These findings provide valuable information about the comorbid disorders in children and adolescents with a very large clinical sample of ADHD children.