Four patients with cardiorespiratory failure caused by secondary kyphoscoliosis were studied. Polycythemia, cor pulmonale, restrictive lung pattern (functional residual capacity (FRC), 17 to 27% predicted; vital capacity (VC), 11 to 23% predicted), and abnormal arterial blood gases, primarily hypoventilation (PaO2, 31 to 44 mm Hg; PaCO2, 52 to 73 mm Hg), were seen in all. Supplementary oxygen, digoxin, diuretics, 15 min of intermittent positive-pressure breathing with inspired pressure (PI) 25 cm H2O 4 times daily, and tracheostomy failed to produce improvement. However, 12 h of nighttime ventilation (NTV) with PI 28 to 35 cm H2O through a permanent tracheostomy proved effective. Within 72 h, dyspnea at rest, restless sleep, and frequent waking resolved. Within 8 to 22 days, the PaO2 was approximately 58 mmHg and the PaCO2 was approximately 41 mm Hg while breathing 21% oxygen spontaneously during the day. The right heart failure resolved within 2 to 7 wk, and the hemoglobin count decreased to approximately 165 g/L within 2 to 6 months. There was a mean increase of 700 ml (72%) in functional residual capacity and 430 ml (49%) in vital capacity. The patients were discharged 2 days to 5 wk after NTV commenced. Daytime activity increased, approaching a normal life style. The improvement was sustained over a mean follow-up period of 3.4 yr. Problems included recurrent episodes of tracheobronchitis, mild self-limiting hemoptysis, and speech modification. Nighttime ventilation may be an effective alternative for long-term treatment of cardiorespiratory failure caused by secondary kyphoscoliosis.