Patients who do not respond to autologous stem cell transplantation (ASCT) have a poor prognosis. Concerns about toxicity limit the use of unrelated donor stem cell transplantation (UDSCT), but the knowledge about outcome after UDSCT post-ASCT is limited. We carried out a retrospective analysis of the outcome in seven consecutive patients with leukemia (n = 5), myeloma (n = 1) and graft failure (n = 1) who underwent UDSCT after ASCT. Donors were matched for HLA-A, -B and -DR (n = 6) or had one class I antigen mismatch (n = 1). Tissue typing was performed by a high-resolution genomic technique for class II. Median patient age was 34 (11-54) years and time from ASCT to UDSCT was 16 (3-22) months. Patients with malignant diseases were given TBI and a CY preparatory regimen. In addition, all patients received T cell antibodies prior to UDSCT. Grade I acute GVHD developed in all seven patients, but there was no sign of more severe acute GVHD. Two of four evaluable patients developed limited chronic GVHD. Three died of transplant-related toxicity, all due to pulmonary complications. Four patients are alive at 1.1, 1.5, 3.1 and 4.9 years post-UDSCT. A closely matched UDSCT could be considered for selected patients who are not cured by an ASCT.