Investigations of long-term outcomes have been instrumental in designing safer and more effective contemporary therapies for pediatric hematological malignancies. Despite the significant therapeutic changes that have occurred over the last five decades, therapy modifications largely represent refinements of treatment protocols using agents and modalities that have been available for more than 30 years. This review summarizes major trends in the evolution of treatment of pediatric hematological malignancies since 1960 to support the relevance of the study of late effects of historical therapeutic approaches to the design and evaluation of contemporary treatment protocols and the follow-up of present-day survivors. Pediatr Blood Cancer 2012; 58: 334–343. © 2011 Wiley Periodicals, Inc.