BACKGROUND State Medicaid programs were established to care for the poor by eliminating financial barriers that otherwise prevent them from being treated in the mainstream health care system. The number of children eligible for Medicaid services is increasing, yet the number of Medicaid providers remains low. Health care providers cited failed appointments as a major problem with Medicaid patients and a great deterrent to participating. The purpose of this study was to determine whether a difference in appointment-keeping behavior exists between Medicaid and non-Medicaid orthodontic patients. METHODS During a 12-month period, a tally of appointments was kept for all active patients (n = 707) at Virginia Commonwealth University's Department of Orthodontics. Patients were categorized as either Medicaid or non-Medicaid, and their appointment-keeping behavior was evaluated. RESULTS A significant difference was found in the number of failed appointments between the groups. The Medicaid patients failed 247 (15.4%) of 1609 appointments, and the non-Medicaid patients failed 367 (8.3%) of 4438 appointments. Medicaid patients accounted for 26.6% of all appointments but were responsible for about 40% of all appointment failures. In addition, 104 (56.2%) of 185 Medicaid patients missed 1 appointment or more during the year, compared with 211 (40.4%) of 522 non-Medicaid patients. CONCLUSIONS The findings from this study support the concern among dental practitioners and orthodontic specialists that Medicaid patients have a higher rate of appointment failures than non-Medicaid patients, although the frequency of missed appointments was substantially lower for orthodontic appointments than that reported for general dental appointments.