We report a case of a patient with multiple myeloma and engraftment failure after high-dose therapy with autologous stem cell transplantation. After rescue treatment with G-CSF and back-up reinfusion of autologous stem cells failed, allogeneic umbilical cord blood transplantation resulted in neutrophil engraftment on day +16 and a 57 months lasting complete remission. This case report shows that umbilical cord blood transplantation is a rescue option after engraftment failure of autologous transplantation, which is available for 99% of patients due to the less stringent HLA matching criteria. Moreover, the prompt availability allows transplantation to be performed at an optimal time.