Objective: To study the psychiatric comorbidity of a clinical sample of children with ADHD and the psychiatric disorders in their parents. Method: Structured psychiatric interviews assessing lifetime psychiatric disorders by "DSM-IV" criteria, using the Farsi version of the Schedule for Affective Disorders and Schizophrenia. Results: The mean age of the children was 8.7, mothers, 40.1, and fathers, 34.6 years. Only 7.6% of the boys and 21.7% of the girls manifested ADHD without any other psychiatric comorbidity. The most common comorbid disorders were disruptive behavior disorders and anxiety disorders. The prevalence of lifetime ADHD in the parents was 45.8% and 17.7%, respectively. The rate for major depressive disorder in mothers and fathers was 48.1% and 43.0%, respectively. Discussion: The clinical sample of ADHD children typically had at least one other psychiatric disorder, usually oppositional defiant disorder in boys and anxiety disorders in girls. The most common psychiatric disorder in the parents was mood disorder. (Contains 2 tables.)