Objective: To investigate the prevalence of overweight and obesity in children and adolescents with ADHD and compare to other clinical samples. Method: A retrospective chart reviewing of 165 ADHD and 305 other clinical participants aged 6 to 18 years. Results: There was no statistically significant difference in terms of the prevalences of overweight and obesity between ADHD and other clinical participants. In ADHD group, the prevalences of overweight, obesity, and combined overweight/obesity were 15.8%, 20.0%, and 35.8%, respectively. In addition, male gender was significantly associated with increasing the prevalences of overweight and obesity in children and adolescents with ADHD. Conclusion: The prevalences of overweight and obesity between ADHD and other clinical samples were not different in a clinical setting. Male gender was significantly associated with increasing the prevalences of overweight and obesity in children and adolescents with ADHD.