Objective: Assessment of the prevalence of overweight and obesity in children and adolescents with ADHD with emphasis on pharmacological treatment and comorbid disorders. Method: We analyzed 408 medical records of patients with ADHD aged 7 to 18. Results: The prevalence of overweight (14.71% vs. 12.83%, ² = 3,586.43, p < .001) and obesity (6.37% vs. 3.45%, ² = 3,588.19, p < .001) was significantly higher in children with ADHD compared with the population. There was significantly higher incidence of obesity in patients with comorbid diagnosis of adjustment disorder (22.22% vs. 4.42%, ² = 5.66, p = .02) and mental retardation (19.05% vs. 4.42%, ² = 7.63, p = .005). Pharmacological treatment was associated with a higher incidence of obesity (8.37% vs. 2.76%, ² = 4.92, p = .03). Conclusion: Standardized body mass index (BMI), prevalence of overweight, and obesity was higher in patients with ADHD compared with the population. Higher incidence of obesity was shown in patients with analyzed comorbidities.