Continuous positive airway pressure (CPAP) is used to treat patients with the obstructive sleep apnea syndrome (OSAS). The current standard is for an attendant technician to titrate CPAP during full polysomnography to obtain a fixed single pressure. The patient uses CPAP nightly at this fixed single pressure. Recently, devices using new technology that automatically titrate positive airway pressure (APAP) have become available. Such devices continually adjust pressure, as needed, to maintain airway patency (APAP titration). These adjustments can be made with or without attendant technician intervention. Data obtained during APAP titration can be used to provide a fixed single pressure for subsequent treatment. Alternatively, APAP devices can be used in self-adjusting mode for treatment (APAP treatment). A task force of the Standards of Practice Committee of the American Academy of Sleep Medicine reviewed the available literature. Based on this review, the Standards of Practice Committee developed these practice parameters as a guide to the appropriate use of APAP. Recommendations are as follows: 1) A diagnosis of OSAS must be established by an acceptable method. 2) APAP titration and APAP treatment are not currently recommended for patients with congestive heart failure, significant lung disease (e.g., chronic obstructive pulmonary disease), daytime hypoxemia and respiratory failure from any cause, or prominent nocturnal desaturation other than from OSA (e.g., obesity hypoventilation syndrome). In addition, patients who do not snore (either due to palate surgery or naturally) should not be titrated with an APAP device that relies on vibration or sound in the device's algorithm. 3) APAP devices are not currently recommended for split-night studies since none of the reviewed research studies examined this issue. 4) Certain APAP devices may be used during attended titration to identify by polysomnography a single pressure for use with standard CPAP for treatment of OSA. 5) Once an initial successful attended CPAP or APAP titration has been determined by polysomnography, certain APAP devices may be used in the self-adjusting mode for unattended treatment of patients with OSA. 6) Use of unattended APAP to either initially determine pressures for fixed CPAP or for self-adjusting APAP treatment in CPAP naïve patients is not currently established. 7) Patients being treated with fixed CPAP on the basis of APAP titration or being treated with APAP must be followed to determine treatment effectiveness and safety, and 8) a re-evaluation and, if necessary, a standard attended CPAP titration should be performed if symptoms do not resolve or the CPAP or APAP treatment otherwise appears to lack efficacy.