It has been reported that cord blood transplantation (CBT) for patients with aggressive adult T-cell leukemia/lymphoma (ATL) results in poorer outcomes than transplantation using other stem cell sources. To identify a subset of ATL in which CBT is feasible, we retrospectively analyzed 27 patients treated with CBT at three institutions in Nagasaki Prefecture, Japan. The estimated overall survival (OS) rate at 3 years was 27.4 %. Of 16 patients who received CBT during remission (complete, CR, or partial, PR), the OS rate at 3 years was 50 %, while during refractory periods (non-CR or non-PR), the OS rate was 9.1 %. Reduced intensity conditioning (RIC) was given to 18 patients, and myeloablative conditioning (MAC) was used in nine, with 3-year OS of 50.0 and 0 %, respectively. Of the 19 deaths, nine were due to progressive disease, eight (five MAC and three RIC) to infection, and two to multiple organ failure. These results suggest that CBT provides similar results with those in other transplantation procedures for selected ATL patients, such as those in CR or PR. Further studies are needed to evaluate the use of CBT in aggressive ATL.