Sixty-four (48%) of 133 children with hematologic malignancy who were admitted to three pediatric ICUs died. Children who required management because of airway obstruction or after general anesthesia had the best outlook (mortality rate of 7% or less); those children who required major circulatory support or mechanical ventilation for hypoxemia did poorly (mortality rate of 84% or greater). Certain conditions in children with hematologic malignancy that require intensive care are associated with a mortality rate of approximately 75%. These include the following: suspected sepsis, interstitial pneumonitis, encephalopathy due to sepsis or hemorrhage. In children with these life-threatening conditions, therapy must be improved because at this stage, the patients do not benefit from admission to the ICU.