OBJECTIVE Patients' and parents' expectations are important in orthodontic treatment decision making. The literature generally demonstrates the perceived benefits of orthodontic treatment, but patients' and their parents' concerns about orthodontic treatment have not been investigated comprehensively. The aim of this study was to identify patients' and parents' concerns about orthodontic treatment and compare them according to sex, age, and treatment demand level. METHODS One hundred and eighty-nine children and their parents were interviewed about concerns related to orthodontic treatment. Patients and parents were asked about orthodontic treatment decisions. Answers were recorded as "yes," "no," or "don't know." Chi-squared and Fisher's exact tests were used to compare concerns between age groups, sexes, and treatment demand levels. Kappa statistics were used to assess agreement between patients and their parents. RESULTS Concerns about orthodontic treatment were gathered under 10 items as follows: "feeling pain," "the appearance of braces," "being teased," "avoiding smiling," "speech problems," "dietary changes," "problems with transportation," "economic problems," "long treatment duration," and "missing school." There was no statistically significant difference in concerns between the sexes or age groups. Some concern items and treatment demand were inversely related in patients. CONCLUSIONS The results of this study demonstrate patients' and parents' concerns about orthodontic treatment. Differences between the concerns of patients with different treatment demands imply that children might reject orthodontic treatment because of their concerns. Appropriate consultation of patients addressing their concerns may help reduce anxiety and improve the acceptance of treatment.