Peripheral blood values and bone marrow appearances were monitored in eight patients treated for chronic granulocytic leukaemia in transformation by cytotoxic drugs with or without total body irradiation followed by autografting with cryopreserved-thawed peripheral blood nucleated cells. One of the patients was 'autografted' on two occasions. Five patients had been splenectomized early in the first chronic phase and the other three patients had their spleens intact. Recovery of peripheral blood values was more rapid in the splenectomized than in the non-splenectomized patients. CFUc were present in the circulation immediately after autografting in each case but subsequently the pattern of CFUc changes differed between patients. The bone marrow was hypocellular at the time of autografting but the rate at which it returned to a typical chronic phase picture varied. Peripheral blood nucleated cells collected at the time of diagnosis include stem cells with the capacity to repopulate the marrow after 'ablative' therapy for transformation. Elective splenectomy in the chronic phase may promote more rapid recovery of peripheral blood values but its long-term importance is unknown.