The majority of children and some adults with acute lymphocytic leukaemia (ALL) can be cured with current intensive chemotherapy regimens. For those patients who relapse or who do not achieve remission, allogeneic haemopoietic stem cell transplantation (HSCT) offers the best chance for long-term disease control. Different sources of haemopoietic stem cells including marrow, peripheral blood, and cord blood are now available and the introduction of subablative regimens has increased the number of patients who are transplant candidates. Relapse remains the major cause of transplant failure and immunotherapy strategies post-transplant to augment the graft versus leukaemia effect are being explored.