The objective of this study was to update the role of different modalities of haematopoietic progenitor cell transplants (PCT) in the therapy of acute leukaemias in children emphasizing the points of agreement and controversy. In AML in first remission, allogeneic PCT from an HLA-identical sibling is the treatment of choice in most cases, DFS of 60-80% has been attained in paediatric series. Indications appear clear except in M3 subtype, M7 in children with Down syndrome and possibly in patients with M2 and t(8;21) and MS-Eo and inv(16) who have a good early response to induction treatment. In some paediatric series, results with autologous transplants (APCT) are similar to those obtained with allo-PCT and superior to those obtained with chemotherapy alone, but this point is controversial. Allo-PCT and APCT are indicated in children in second remission, yielding 40% DFS. In children with ALL in first remission, indications for PCT are limited to only 8-10% of patients with very-high risk of relapse, mainly those with certain chromosome abnormalities or with poor or late response to induction treatment; a favourable outcome has been registered in 60%. Allo-PCT is the best choice for patients in second remission after an early marrow relapse and who have an adequate related or unrelated donor; DFS of 40-50% has been described in several paediatric series. Indications of allo-PCT from related donors after late bone marrow relapses or early extramedullary relapses appears more controversial but there are data in its favour. The role of APCT appears even more controversial but some authors favour its use in these situations. In more advanced stages of the disease the results obtained with allo-PCT are poorer (DFS between 10 and 20%). In summary, although many controversial points with regards to indications and modalities of transplants in acute leukaemia in children remain, it must be emphasized that with advances in both fields, chemotherapy and transplants, today 80% of children with ALL and 60-70% of those with AML are cured and enjoy good-quality of life.