We studied the need for mechanical ventilation in 265 patients with respiratory failure who came to our medical ICU over the past 3 years. The time required for weaning from mechanical ventilation and the percentage of patients who needed oxygen therapy or mechanical ventilation at home after their condition was no longer acute were also studied. Of the patients treated in the medical ICU, 143 (54%) required mechanical ventilation; 104 (39%) had acute respiratory failure and the others had acute exacerbations of chronic respiratory failure. Some causes of acute respiratory failure were aspiration pneumonia, bronchial asthma, and drug use. Three-fourths of those with chronic respiratory failure had pulmonary emphysema, sequela of pulmonary tuberculosis, or idiopathic interstitial pneumonia. In patients with chronic respiratory failure, success in weaning could be predicted from the respiratory index (PaO2/FIO2), the serum albumin level, and the length of time that they were ventilated with more than 60% oxygen. Thirteen patients with chronic respiratory failure died while receiving mechanical ventilation. Of those who survived, 11 underwent tracheostomies, and 4 of those 11 were mechanically ventilated at home with portable devices. Ten other survivors received home oxygen therapy. Chest physicians bear the greatest responsibility for managing mechanical ventilation in medical emergencies. Moreover, the prognosis for patients with chronic respiratory failure can be improved with a long-term program for respiratory care that includes home mechanical ventilation and home oxygen therapy.