Relapsed/refractory B-precursor ALL in adult patients is an aggressive malignant disease with dismal prognosis. Several studies have reported long term survival to be below 10%. Major prognostic factors are duration of first complete remission (CR1) and age. With current salvage chemotherapy, complete remission (CR) rate is low (20 to 30%) in patients in first salvage with short duration (< one year) of first remission, patients relapsed after first salvage, or patients aged 60 years and older. Duration of CR is usually very short (median disease free survival [DFS]: 2.0-7.5 months). Allogeneic hematopoietic stem cell transplantation (HSCT) may provide a curative treatment option for patients in CR with a satisfactory donor and appropriate clinical status including age, organ function, and remission status. Allogeneic HSCT is not an option in most elderly patients with relapsed ALL. Additional therapeutic approaches are urgently needed.