The pulmonary function test plays an important role in the management of pulmonary complications after bone marrow transplantation. Although its utility in helping to predict the likelihood of developing post transplant pulmonary complications and mortality is not well established, current data indicate that pre-transplant pulmonary function tests are important as a reference for the interpretation of post transplant pulmonary function tests and for identifying patients at high risk of developing pulmonary complications and/or mortality after bone marrow transplantation.