Relapse is one of the main problems which can occur following allogeneic transplantation for haematological malignancies. In this situation the enhancement of the graft-versus-leukaemia effect by transfusion of donor buffy coats with or without cytokines may lead to complete remission especially in myeloid leukaemias. FISH (fluorescence in situ hybridization) is a sensitive method to monitor chimaerism in gender-different transplantation. We report a case of successful buffy coat transfer therapy > 9 years after bone marrow transplantation. This is the longest interval reported, to our knowledge, between transplantation to relapse, which was treated by adoptive immunotherapy. Complete donor chimaerism was confirmed by FISH.