Over the past decade, allogeneic cord blood transplantation (CBT) has been widely used for treating patients with malignant disorders. However, the reported low incidence of GVHD observed after allogeneic CBT might be a major drawback in leukemic recipients and at present it is not clear whether CBT really predisposes patients to an increased risk of leukemia relapse. In order to further elucidate the role of CBT in children with hematological malignancies, 54 patients with ALL or AML given either a related (31 cases) or an unrelated (23 cases) CBT in 25 centers participating in the Eurocord Registry were analyzed. Overall survival of related and unrelated CBT recipients was substantially similar, the most important factor influencing patients' outcome being disease state at time of transplantation. In fact, due to a markedly increased relapse rate, poor-risk children (ie patients transplanted in more advanced disease) experienced a significantly worse EFS than those given CBT in a more favorable disease phase (ie CR1 or CR2). These data confirm that allogeneic CBT from either a related or an unrelated donor is a feasible procedure able to cure a significant proportion of children with acute leukemia, especially if transplanted in a favorable phase of disease.