Newly diagnosed patients who have advanced-stage Hodgkin's lymphoma have an excellent prognosis because most of them can be cured with initial treatment. In contrast, the prognosis for patients relapsing after first-line therapy with either combination chemotherapy or chemotherapy followed by radiotherapy remains poor in many cases. In most of these cases, high-dose chemotherapy and autologous stem cell transplantation (ASCT) is currently considered to be the treatment of choice. However, results of ASCT in primary refractory patients are poor and new therapeutic alternatives should be sought for these patients. Allogeneic stem cell transplantation has been used increasingly in relapsed or refractory Hodgkin's lymphoma patients, with the introduction of reduced-intensity conditioning protocols.