Respiratory failure is a recognized complicationm of both bone marrow and solid-organ transplant. Patients who require mechanical ventilation after bone marrow transplant have a high mortality. Recent studies have focused on 1) describing clinical scenarios likely to result in respiratory failure, 2) assessing potential predictors of respiratory failure, and 3) evaluating diagnostic approaches. Solid-organ transplant recipients are moist likely to develop respiratory failure secondary to infectious complications. Aggressive prophylaxis has greatly improved the outlook in many cases; however, emerging organisms, particularly fungal organisms, remain a significant threat. Lung transplants are particularly susceptible to early reperfusion injury and late obliterative bronchiolitis. Extracorporeal membrane oxygenation has been successfully used to support patients with severe reperfusion injury. Obliterative bronchiolitis is a more difficult problem that is still being completely characterized and that has responded only modestly to treatment attempts.