The large and growing numbers of patients with obstructive sleep apnea syndrome (OSAS) attending sleep disorders clinics create major logistical difficulties for the follow-up of these patients, particularly those on nasal continuous positive airway pressure therapy (CPAP). Follow-up of patients on CPAP should focus on treatment efficacy, side effects, and compliance with therapy. The adequacy and comfort of mask fit and the appropriate selection of pressure level at the time of initial titration have a major influence on treatment efficacy. Outcome measures of treatment efficacy include improvements in daytime performance and quality of life measures in addition to impact on cardiovascular morbidity, particularly hypertension. Side effects and compliance with CPAP are also influenced greatly by the adequacy of mask fit and pressure selection, which underlines the great importance of adequate technical expertise and patient education at the time of initiation of therapy. The recent development of automatically adjusting CPAP devices should greatly simplify the initiation of CPAP therapy and also the subsequent follow-up of OSAS patients on CPAP therapy. However, the much higher cost of auto-CPAP devices compared to standard CPAP does not justify the routine use of these more expensive devices at this time.