Patients with chronic obstructive pulmonary disease (COPD) are prone to exacerbations of respiratory failure that are associated with a poor prognosis, especially if the patient requires tracheal intubation in the intensive care unit. Acidosis is an important prognostic factor for exacerbations of respiratory failure in COPD and thus acidosis requires correction as soon as possible in the patient. Techniques of noninvasive positive pressure ventilation (NIPPV), using either nasal masks or face masks, have been developed that can be used on general wards and avoid the complications related to tracheal intubation. NIPPV has been shown to improve gas exchange and produce early correction of acidosis in exacerbations of respiratory failure. Recent controlled studies have shown that rates of tracheal intubation, length of hospital stay, and mortality can be significantly reduced with NIPPV compared with standard therapy. For maximal effectiveness, a trial of NIPPV should be considered early in the course of the respiratory failure, when the pH falls below 7.35. Successful implementation of NIPPV will lead to the reduction in morbidity and mortality associated with severe COPD and will allow ven-tilatory support to be used on a general ward in patients who are regarded as unsuitable for tracheal intubation in the intensive care unit.