Decompensated chronic obstructive pulmonary disease (COPD) is likely to remain a common medical emergency for the foreseeable future. Decompensation occurs when the capacity of the respiratory muscle pump is less than the load placed upon it. Even with optimal medical therapy, the mortality rate remains high. Noninvasive positive pressure ventilation (NIV) is a new technique, which is increasingly used as an alternative to mechanical endotracheal ventilation (ETV). In this review we discuss the existing literature, consider unresolved areas for future research and describe practice in our own hospital.