The diagnosis of acute leukemia was a virtual death sentence less than 30 years ago. A patient with this diagnosis had an expected median life span of less than three months, and had a greater than 90% probability of being dead within a year of diagnosis. It rated as one of the most dreaded and most malignant of the malignant diseases. The discovery of the first antimetabolite, methotrexate, and the subsequent discovery of other new effective drugs led to rapid improvement in the outlook for children with acute leukemia.1 By 1965, virtually every child with that diagnosis would respond to treatment with complete hematologic and clinical remission, and a substantial proportion would be expected to have prolonged survival.2 Several studies have suggested that 10% to 30% of patients might be surviving more than five years after diagnosis and might even be considered as potentially curable.3,4 However, the