The development of oral appliance treatment for OSA represents an important step in the management of this disease. Randomized, controlled clinical trials have shown them to be an effective treatment option for snoring and OSA in some patients, particularly patients with less severe OSA or simple snoring and patients who have failed other treatment modalities. Although oral appliances are not as effective as CPAP therapy, they work in most patients to relieve symptoms and apnea and are well tolerated by patients. Most patients report improvements in sleep quality and excessive daytime sleepiness. Short-term side effects are generally minor and are related to excessive salivation, jaw and tooth discomfort, and occasional joint discomfort. These symptoms may lead to discontinuation of appliance therapy but usually improve in most patients over time. Serious complications are not common, but occlusal changes are more common than previously believed.