A patient with acute myelogenous leukemia developed pulmonary alveolar proteinosis in the terminal phase of the leukemia. The diagnosis of pulmonary alveolar proteinosis was unsuspected during life and was established only at autopsy. Other reported cases of the same association are reviewed. This report serves to stress the importance of considering the diagnosis of pulmonary alveolar proteinosis in malignant hematologic diseases and the need for hematologic evaluations in pulmonary alveolar proteinosis.