OBJECTIVES: In the treatment of obstructive sleep apnea/hyoponea syndrome (OSAHS) moderate patients are primarily offered Continuous Positive Airway Pressure (CPAP). This study aims to assess the cost-effectiveness of mandibular advancement device (MAD), a commonly suggested alternative, as compared to CPAP for moderate OSAHS patients in the Netherlands. METHODS: The prognosis of a hypothetical cohort of 50-year-old patients with moderate OSAHS was simulated with a Markov model to estimate the costs and quality-adjusted life-years (QALYs) for both CPAP and MAD. A distinctive factor incorporated in the model was switch of therapy. All input parameters, including the risks of experiencing myocardial infarction, stroke and motor vehicle crashes (MVC) were based on literature and clinical expert opinion. Costs and effects were estimated over a 5-year time horizon using a healthcare provider perspective and were discounted at a rate of 4% and 1.5%, respectively. Robustness of the results was investigated with several sensitivity and scenario analyses. RESULTS: Compared with CPAP, MAD is less expensive (€4,511 vs €5,302) and only slightly less effective (3.44 vs 3.49 QALYs) resulting in an incremental cost-effectiveness ratio (ICER) of €15,393 saved per QALY lost. The most influential parameter was the cost of MAD device and its titration. Quality-of-life values, compliance rates, costs and the probabilities of switching treatment, cardiovascular events and MVC were varied in the scenario analyses. Under the majority of the scenarios MAD remained less cost-effective compared to CPAP. CONCLUSIONS: Over a 5-year time horizon, MAD therapy may be considered not cost-effective in the treatment of moderate OSAHS patients in the Netherlands. Further research on the impact of both treatments on long-term risks and improvement in the quality of life is required. Similarly, more long-term studies using a uniform compliance definition are needed to inform future cost-effectiveness analyses.