Objective: Our aim was to evaluate the Quality of Life (QoL) of treatment naïve children with ADHD. Method: Data from 178 parent–child dyads were analyzed using multiple regression to assess the relationships between QoL, and characteristics of ADHD and comorbid psychopathology. Results: Lower self-reported QoL was associated with female gender, higher age, more symptoms of anxiety and trauma-related disorders in dimensional approach, and with the comorbid diagnoses of trauma-related disorders and oppositional defiant disorder (ODD)/conduct disorder (CD) in categorical approach. Lower parent-reported QoL was related to older age and increasing number of symptoms of mood and anxiety disorders on one hand, and any diagnosis of mood and anxiety disorders and ODD/CD on the other. Conclusion: Our results draw the attention to the importance of taking into account age, gender, and both self- and parent reports when measuring QoL of children with ADHD and both dimensional and categorical approaches should be used.