Background and Purpose: Attention Deficit Hyperactivity Disorder (ADHD) is the most common neurodevelopmental disorder in children. The purpose of this study is to explore the rate of psychiatric comorbidities among children with ADHD and investigating the impact of comorbidities on function of children. Subjects and Methods: Sixty-four children of both genders who fulfilled DSM-5 criteria for ADHD were included. All subjects were subjected to IQ assessment, Kiddie Schedule for Affective Disorders and Schizophrenia (K-SADS), Conners Rating Scale, and Child Behavior Check List (CBCL). Results: Combined subtype was the commonest (50%) followed by hyperactive-impulsive (31.25%), then inattentive (18.75%). Psychiatric comorbid disorder among pediatric cases with ADHD was ODD (31.25%), followed by nocturnal enuresis (23.44%), conduct disorders (18.75%), motor tic disorders (15.63%), anxiety disorders (12.50%), depressive disorders (10.94%), substance abuse disorders (9.38%), autism spectrum disorders (7.81%), vocal tic disorders (1.56%).  There was a statistically significant difference between gender and conduct disorder and SUDs (P <0.05). There was no significant difference in the distribution of comorbidities among subtypes except for conduct disorder (P<0.05). There was a significant difference between comorbidities and severity of ADHD, according to the Conners scale (P<0.05). There was a significant difference between comorbidities number and different CBCL parameters (P<0.05). There was a significant negative correlation between the number of comorbidities and total competence and positive correlation with the total problem (P<0.05). Conclusions: The presence of comorbid disorders among pediatric cases with ADHD is the rule rather than the exception. Oppositional defiant disorder, followed by nocturnal enuresis, are the most common comorbid diseases. Comorbidities number is negatively correlated with total competence and positively correlated with the total problem.