['Oral appliance (OA) therapy is considered a first line choice of therapy for some patients with mild or moderate obstructive sleep apnea (OSA) and an alternative form of treatment in those intolerant of continuous positive airway pressure (CPAP) use. According to several studies, periodic limb movements (PLM) appear during effective treatment of OSA with CPAP, but a similar phenomenon has not been described with the use of oral appliance. Herein, we describe the incidence of PLM in patients with OSA who underwent oral appliance therapy titration.', 'This is a retrospective, [corrected] observational study set in a six-bed sleep center in an academic, military referral hospital.', 'Patients with OSA (n=21; 15 men and six women; mean age, 43 years; and age range, 25 to 53 years) treated with OA during a 1-year period were analyzed. [corrected] Patients were categorized according to the severity of sleep apnea and incidence of PLM on diagnostic polysomnography. Effective treatment of OSA and appearance or disappearance of PLM with arousal on subsequent oral appliance titration polysomnography were recorded and compared.', 'Twenty-one patients were included in the analysis. [corrected] During baseline polysomnography, three of 21 (14%) patients had five or more PLM with arousal per hour while 11 of 21 (52%) patients had PLM with arousal during the oral appliance titration trial.'] Does oral appliance titration in patients with obstructive sleep apnea induce the appearance of periodic limb movements?