BACKGROUND AND OBJECTIVES: We analyzed outcomes and risk factors after unrelated cord blood transplantation (CBT) in adults with hematologic malignancies. DESIGN AND METHODS: One hundred and seventy-one patients were transplanted after 1997. Their median age was 29 years (15-55), and the median follow-up time was 18 months (1-71). Most patients had acute or chronic leukemia (n=142, 83%), 91 (53%) were transplanted in advanced phase and an autologous transplant had failed in 32 (19%). Most patients (87%) received an HLA-mismatched cord blood unit with 1-2 HLA disparities. At infusion, the median number of nucleated cells and CD34(+) cells was 2.1x10(7)/kg and 1x10(5)/kg, respectively RESULTS: The cumulative incidence of neutrophil recovery at day 60 was 72+/-3% with a median of 28 days (11-57). A higher neutrophil count and use of hematopoietic growth factors were independently associated with faster neutrophil recovery. The cumulative incidence of grade II-IV acute graft-versus-host disease was 32+/-4% and this complication was not associated with the number of HLA mismatches. The 2-year cumulative incidence of chronic graft-versus-host disease, transplant related-mortality and relapse were 36+/-10%, 51+/-4% and 22+/-4%, respectively. At 2-years, disease-free-survival for patients transplanted in early, intermediate and advanced phases of disease was 41+/-9%, 34+/-10% and 18+/-4%, respectively. In multivariate analyses, advanced disease status was an adverse factor for relapse and disease-free survival. INTERPRETATION AND CONCLUSIONS: Unrelated CBT is a clear alternative for adults with hematological malignancies lacking an HLA-matched related or unrelated donor. The choice of units containing a higher neutrophil count and a policy of earlier transplantation are likely to provide better results.