OBJECTIVE: To compare the prevalence of problematic internet use (PIU) in attention deficit hyperactivity disorder (ADHD) and non-ADHD children and explore the related factors and effects of PIU in children.METHODS: A cross-sectional study was done. ADHD and non-ADHD participants aged 7-15 years old with current internet use were enrolled. A self-report questionnaire collected child and parental demographic data, internet use, and related data. An internet addiction scale was used.RESULTS: A total of 127 participants were enrolled, including 56 ADHD participants and 71 non-ADHD participants. The rate of possible PIU and PIU (possible PIU/PIU) in the ADHD group was 60.7% and 61.5% in the non-ADHD group. In the ADHD group, internet usage time ≥ 21 hours per week was a significant related factor to possible PIU/PIU (adjusted odd ratio 27.08, 95% confidence interval 2.35 – 312.04). Male was significant related factor to possible PIU/PIU in the non-ADHD group (adjusted odd ratio 4.25, 95% confidence interval 1.25 - 14.47). School level, grade, online gaming or social media exposure, and parental internet restriction were non-significant related factors in both groups. Children with possible PIU/PIU had significantly more positive depressive symptoms than the normal internet use group (p = 0.006).CONCLUSION: The results indicate a higher rate of possible PIU/PIU in both groups and a significant relation with depressive symptoms. In routine practice, we should clarify this issue and provide education to families and children with or without ADHD to prevent internet related problems.