Past literature has shown that respiratory failure following hematopoietic stem cell transplant is associated with a universally poor outcome with mortality rates approaching 100%. More recent studies have suggested that patient survival is improving. We report our experience with the patients from our institution, a large children's hospital, who were admitted to the intensive care unit (ICU). Medical records of 183 patients, who received a bone marrow transplant between 1992 and early 2004, who were <20 yr of age, were retrospectively reviewed. Various factors that might influence mortality were examined. Over the course of the study, the ICU survival increased from 18% during the period 1992-1999 to 59% between 2000 and early 2004. In the latter period, 54% of the patients discharged from the ICU were alive at 100 days post-transplant. Factors that were significant predictors of poor outcome were malignancy as the reason for transplant, dialysis during the ICU stay, or extreme respiratory failure with a ratio of arterial oxygen tension (PaO2)/inspired oxygen concentration (FiO2) <300. Analysis of patients who required a high positive end-expiratory pressure or were ventilated with permissive hypercapnia showed that they also had a higher mortality. The impact on survival of factors such as age at time of transplant, graft-vs.-host disease, pneumonia, bacteremia, sepsis, post-transplant days, Pediatric Risk of Mortality III score, engraftment status, or veno-occlusive disease did not reach statistical significance in this cohort. Survival has improved for children who require intensive care following a bone marrow transplant, even for those who require mechanical ventilation. Patients with extreme respiratory failure and those requiring dialysis continue to have poor outcome. Because of an overall improvement in survival, children whose condition following transplant requires intensive care should be treated aggressively.