Background: Oral appliance therapy for obstructive sleep apnea can be helpful in mild and moderate cases. This clinical report evaluates the efficacy of a protocol that predicts an optimal jaw position and describes the response of a young OSA patient to treatment. Clinical Presentation: A 27-year-old woman was diagnosed with moderate OSA and had an apnea?hypopnea index (AHI) of 25.8/hr. In order to fabricate a custom device, an alternative procedure to determine the optimal protrusion and vertical positioning of the jaw was applied. After a follow-up period of 14?months, her apnea-hypopnea index (AHI) significantly decreased from 25.8 to 1.0 per hr with the appliance. The total number of respiratory events decreased from 211 to 8. Conclusion: Improved polysomnographic parameters showed that the oral device was efficient in treatment. The advantages of the device in this study are that it is comfortable, economical, and simple to fabricate.