Continuous positive airway pressure via the nasal route (nasal CPAP) is effective in reducing the frequency of occlusive and mixed patterns of sleep apnea. Little is known about long-term patient compliance with this therapeutic modality, however. In order to evaluate this, questionnaires were mailed to 24 sleep apnea patients who had received a nasal CPAP system for nightly use. Patients were requested not to sign the questionnaire. At the time of mailing, the patients had possessed their nasal CPAP equipment for 10.3 +/- 8 months (mean +/- SD). Twenty patients (83 percent) responded to the questionnaire. Sixteen responders used nasal CPAP during all nightly sleep time, and two used it for all but one and 2.5 hours of nightly sleep time, respectively. One individual used it on alternate nights, and one patient did not use it all. Thus, 17 of 20 (85 percent) responders were compliant. Including information about the four nonresponders, obtained by means other than questionnaire, 18 of 24 (75 percent) patients were compliant with therapy. All but two patients were obese at the time sleep apnea was diagnosed. Only 50 percent of questionnaire responders reported weight loss after receiving nasal CPAP, and these individuals were frequent nasal CPAP users. The most common complaints were mask discomfort (14 responders) and nasal dryness and congestion (13 responders). We conclude that long-term home nasal CPAP is a viable therapy that is conscientiously applied and well-tolerated by most sleep apnea patients.