Respiratory virus infections are becoming increasingly appreciated causes of morbidity and mortality in bone marrow transplant recipients. Fred Hutchinson Cancer Research Center (FHCRC) has had considerable experience with respiratory syncytial virus (RSV), parainfluenza, influenza, and rhinovirus infections in these patients over the past decade. Overall, RSV accounted for the majority of community-acquired respiratory virus infections (35%), followed by parainfluenza virus (30%), rhinovirus (25%), and influenza virus (11%). Pneumonia occurred frequently among those infected with RSV (49%) or parainfluenza (22%) but infrequently among those infected with influenza virus (< 10%) or rhinovirus (3%). In one study conducted at FHCRC, intravenous ribavirin was not effective against established RSV pneumonia. In another, ongoing study, however, short-course aerosolized ribavirin appears to reduce progression of upper respiratory tract infection to pneumonia, but further study is needed. Neither strategy had an obvious impact on viral shedding, although persistence of viral shedding did not correlate with either the development or the outcome of pneumonia.