Objective: To determine the changes in dental anxiety, state anxiety, and trait anxiety levels of patients and their parents after 3 months of active orthodontic treatment. Methods: We evaluated 120 patients and one parent of each patient. State Anxiety (STAI-S), Trait Anxiety (STAI-T), and Corah s Dental Anxiety Scale (DAS) were administered before orthodontic treatment (T1) and after 3 months of treatment (T2). Differences in scores between T1 and T2 were compared using paired-sample t-tests and the relationship between the scores of the DAS and the STAI were analyzed using a bivariate two-tailed Pearson correlation test. Results: Dental anxiety and state anxiety levels decreased among the patients after adjustment to orthodontic treatment (p < 0.001). However, 3 months of treatment was not sufficient to decrease the anxiety levels of parents (p > 0.05). Patient trait anxiety affected patient state anxiety and dental anxiety (p < 0.01). Additionally, a significant correlation was found between patient dental anxiety and parent dental anxiety (p < 0.05). Conclusions: Dental anxiety and state anxiety levels decrease after patients become familiar with their orthodontist and they became accustomed to orthodontic treatment. However, 3 months is not a sufficient length of time to decrease parental anxiety levels. [Korean J Orthod 2012;42(4):201-206]