In children and adolescents with chronic myeloid leukaemia (CML) stem cell transplantation (SCT) may be a valid alternative to the life-long treatment with tyrosinkinase inhibitors (TKI). This trial aims to evaluate the use of a reduced intensity conditioning regimen (RIC), consisting of fludarabine, melphalan and thiotepa in order to minimize transplant related mortality and toxic late effects. Strict post-transplant monitoring and reintroduction of TKI as well as donor lymphocyte infusions (DLI) in case of relevant residual disease are part of the protocol.