Abstract: Bone marrow GM-CFC were determined during the course of allogeneic FLT and BMT in 9 cases of acute leukaemia in their first remission. Results suggest that the yield of BM-CFC before transplantation reflects the recovery degree of hemopoietic function which is helpful to formulate the preconditioning regimen, and the continuous observation of GM-CFC after transplantation may be served as monitoring tool for detecting the relapse of leukaemia.