This is a study of the effect of nocturnal nasal intermittent positive pressure ventilation (NIPPV) on symptoms of chronic alveolar hypoventilation (CAH), sleep oxygen saturation (SaO2), and frequency of hospitalization of patients with progressive neuromuscular respiratory insufficiency or restrictive lung disease from thoracic wall deformity. The nocturnal use of NIPPV is explored in combination with other noninvasive methods of supported ventilation for daytime support as alternatives to tracheostomy and long-term tracheostomy intermittent positive pressure ventilation (TIPPV). Sixteen patients with less than 400 ml of vital capacity (VC) supine and less than 15 minutes of autonomous respiration (free time) maintained a mean SaO2 of 95.9 +/- 2.6 percent (SD) during sleep on NIPPV without added oxygen. Seventeen other patients with adequate free time for a sleep trial unaided had an average SaO2 of 81.8 +/- 11.0 percent which improved to 94.1 +/- 3.4 percent on NIPPV alone. The average length of use of NIPPV by the 42 patients who have used it for one month or more is 21 (3-67) months. All 34 patients who were not dependent on ventilatory support 24 hours a day demonstrated significant improvement and in most cases normalization of ABG when off aid. Thirteen patients were converted from IPPV via an endotracheal tube or TIPPV to NIPPV. Long-term use of a custom molded thermoplastic nasal interface for the delivery of NIPPV is reported for 17 patients. Unnecessary morbidity and hospitalizations can be avoided by early awareness and appropriate management of CAH. NIPPV can be an effective alternative to TIPPV, body ventilators, or oxygen therapy.