Objective: The aims of this cross-sectional study were to examine the association between significant ADHD symptoms and the four domains of anxiety symptoms on the Taiwanese version of Multidimensional Anxiety Scale for Children (MASC-T) and to examine the moderating effects of sociodemographic characteristics on this association among Taiwanese adolescents in the community. Method: A total of 4,716 adolescents in Grades 7 through 12 in southern Taiwan completed the MASC-T, the ADHD Self-Rated Scale, the Mandarin Chinese version of the Center for Epidemiological Studies Depression Scale, the Rosenberg Self-Esteem Scale, and a questionnaire about sociodemographic characteristics. Multiple regression analysis was used to examine both the association of significant ADHD symptoms with four domains of anxiety symptoms on the MASC-T and the moderating effects of sociodemographic characteristics on this association. Results: The adolescents with significant ADHD symptoms had more severe total anxiety symptoms, physical symptoms, social anxiety symptoms, and separation/panic symptoms for three domains of the MASC-T but less harm avoidance than did those without significant ADHD symptoms. Age, gender, and low self-esteem had moderating effects on the association between significant ADHD symptoms and anxiety symptoms for some domains of the MASC-T. Conclusion: The results of this study suggest a significant association between significant ADHD symptoms and the severity of anxiety symptoms in adolescents. Clinicians must evaluate anxiety symptoms among adolescents with ADHD and arrange comprehensive treatment programs. (J. of Att. Dis. 2012; XX(X) 1-XX)