Objectives: This study aimed to evaluate the association between internet addiction and Attention- Deficity/Hyperactivity Disorder (ADHD) among senior students in some elementary schools. Methods: Total 1,172 students of 4 elementary schools were chosen. General characteristics, health-related behavior, internet addition(K-scale), and ADHD were collected using self-reported questionnaires. Chi-square tests, t-tests and multiple logistic regression analysis were performed to assess the association between internet addiction and ADHD symptoms. Results: Amongst 1,172 subjects, boy students were 628 (53.6%) and girl students were 544 (46.4%). The prevalence of ADHD was 65 (5.5%). With regard to internet addiction, 157 (13.4%), 106 (9.0%) and 909 (77.6%) of the students were categorized as high-risk group, potential-risk group and normal group, respectively. The odds ratio for ADHD was significantly higher in potentialrisk group (OR=20.08, 95% CI=3.51-114.92) and high-risk group (OR=125.77, 95% CI=24.46- 646.66) than normal group. Also, internet addiction score was significantly associated with ADHD symptoms OR=108, 95%CI=1.06-1.11). Conclusions: Internet addiction was associated with ADHD in late elementary students. Further study is need to investigate the biologic mechanism between internet addiction and ADHD.