We investigated the efficacy of cord blood transplantation (CBT) for adult acute lymphoblastic leukemia (ALL) by reviewing medical records of 256 patients reported to the Japan Cord Blood Bank Network between June 1997 and August 2006. Cumulative incidence of neutrophil engraftment at day 100 was 78%. Infused CD34-positive cell dose (>1 × 10(5) cells/kg) was associated with successful neutrophil engraftment. Cumulative incidence of grade II-IV acute graft-versus-host disease (GVHD) at day 100 was 37%. A 2-year disease-free and overall survival (OS) rates were 36% and 42%, respectively. Multivariate analysis showed that age (51 or older vs younger than 50) (hazard ratio 1.9, 95% confidence interval (CI), 1.3-2.8, P=0.001), disease status (non-remission vs remission) (hazard ratio 2.2, 95% CI, 1.5-3.2, P<0.0001), grade III-IV acute GVHD (hazard ratio 2.0, 95% CI, 1.2-3.2, P=0.006) and absence of chronic GVHD (hazard ratio 2.4, 95% CI, 1.1-5.1, P=0.02) were negatively associated with OS. CBT is effective for some patients with advanced ALL. It is worth considering for further evaluation.