HTLV-1-associated acute adult T-cell leukaemia-lymphoma (ATL) is a highly aggressive malignant disorder with a median survival of 6 months or less. We describe an Afro-Caribbean female with very poor prognosis ATL who underwent chemotherapy with a 4 d infusion schedule of cyclophosphamide, doxorubicin and etoposide, followed by successful allogeneic bone marrow transplantation (BMT) from her HTLV-1-negative histocompatible sister. The patient remains in complete remission 23 months after BMT and has 100% donor haemopoiesis with no evidence of HTLV-1 infection on PCR testing. We suggest that allo-BMT can prolong disease free survival or may even be curative in HTLV patients.