Objectives : The purpose of the study is to investigate the influencing factors on the sleep quality in patients with fixed orthodontic appliances. This study intended to find out the improving measures of sleep quality in orthodontic patients. Methods : The subjects were 222 orthodontic patients in Busan. A self-reported questionnaire was filled out by the patients from June to August, 2012. Data were analyzed by SAS version 9.20 including frequency analysis, ANOVA, t-test, multiple regression analysis, and Duncan post-hoc test. Results : The quality of sleep in the patients at the initial stage of orthodontic treatment was influenced by ceramic orthodontic appliances, tooth extraction, Bite adjustment, disturbed sleep habits, and temporomandibular joint pain. Conclusions : The most important factors influencing on the sleep quality were the anxiety toward the treatment and tooth extraction at the initial stage of treatment. A more careful conversation and collaboration are needed in the orthodontic treatment.