Continuous positive airway pressure (CPAP) is efficacious in the treatment of obstructive sleep apnea syndrome (OSAS) in patients with Parkinson's disease (PD). However, this treatment is often not well tolerated in this disabled population. We explored, in a pilot study, the efficacy, observance, and usability of mandibular advancement device (MAD) for the treatment of OSAS in this peculiar population. Patients/methods: Twenty patients with PD and moderate or severe OSAS were included in the study. Ten patients had refused or not tolerated the validated treatment with CPAP so that they were treated with MAD. The patients treated with MAD were matched for sex, age and body mass index (BMI) to 10 patients with PD treated with CPAP. We explored the efficacy of MAD on sleep disorders complaints (PDSS-2) and on sleep recordings. We compared adherence, tolerance and usability with MAD and with CPAP.Results: MAD improved sleep complaints increasing PDSS-2 scores (85 [55-106] vs 106 [88-126], p < 0.005), and sleep respiratory measures reducing apnea/hypopnea index (AHI) (50.8 [30.0-76.4] vs 9.4 [5.0-45.2], <0.001) and oxygen desaturation index (22.9 [2.1-92.0] vs 3.8 [0.2-34.2], p < 0.05). Observance was higher with MAD than with CPAP. Usability and caregiver satisfaction were higher with MAD than with CPAP whereas side effects were similarly reported.Conclusion: Mandibular advancement device may be an noteworthy alternative treatment of OSAS in patients with PD.