Objective: To investigate comorbidity of oppositional-defiant disorder (ODD), conduct disorder (CD), anxiety, and depression and to investigate the impaired social and academic developments among children with ADHD in primary school settings in Saudi Arabia. Method: Data for the purpose of this study are obtained from parent and teachers of 652 primary school children attending Grades 1 to 3 (children aged between 7 and 9 years). Vanderbilt ADHD diagnostic rating scale, which has relevance and found to be reliable by previous studies, is used in the study. Results: ODD and CD are reported to be present in close to two thirds (73%) of children with ADHD, as assessed with "DSM-IV-TR" criteria. Anxiety and depression disorder are estimated to be present in 36% of children with ADHD. Children with ADHD show high levels of impairment in academic achievements (63%) and social performance (90%), compared with non-ADHD children. Conclusion: These findings suggest that a significant minority of disruptive children may have their difficulties compounded by the presence of ADHD, which raises the question whether their problems are known and whether they have received appropriate help. It is important to develop a specific set of psychological clinical intervention for helping children with ADHD, ODD, CD, and other related problems. Educating teachers and parents about ADHD and its comorbidity is considered essential in this regard. (Contains 4 tables and 1 figure.)