The aim of this study is to review the role of stem cell transplantation in pediatric malignant tumors either hematologic or solid with its impact on survival compared to other treatment modalities, possible treatment related toxicities & future directions. Hematopoietic stem cell transplantation (HSCT) has become the standard of care for several malignant and non malignant hematologic disorders in children. In the 1970s, patients with leukemia were cured using a combination of radiation and chemotherapy, followed by matched sibling HSCT. Recent advances have included improvements in human leukocyte antigen (HLA) typing, allowance for the use of unrelated blood donors, the growth of unrelated blood donor registries, such as the National Marrow Donor Program (NMDP), and improvements in the supportive care of post transplant patients. It is estimated that more than 800,000 HSCTs have been performed worldwide with a total of 55,000 to 60,000 annually. The outcome of HSCT in children depends on the underlying disease and remission status, the type of donor and degree of HLA match, and the health and age of the recipient. The overall 5-year survival rate for children who undergo HSCT for acute myelogenous leukemia is 70% and 50% for those with acute lymphoblastic leukemia. Cure rates for metastatic neuroblastoma are approaching 50% with autologous HSCT and immunotherapy with retinoic acid. Transplantation-related mortality, occurs in 5% to 10% of autologous HSCT, 10% to 20% of matched sibling allogeneic HSCT, and 20% to 40% of unrelated donor allogeneic HSCT.