Pulmonary lavage (mechanical washing of the lung) is gaining acceptance as a treatment for respiratory insufficiency from alveolar proteinosis, asthma, and cystic fibrosis. However, management with this form of therapy can be quite complicated when the patients are critically ill from respiratory insufficiency. As pulmonary lavage represents a physiologic trespass, particular attention must be paid to potentially serious complications; eg, acute hypoxia. Reduction of complications can be achieved by an understanding of the problems involved. Methodology and technical considerations are reviewed and our experience summarized.