The present study was aimed to investigate the effects of bone marrow stromal cell on the growth of granulopoietic progenitors in mice with combined radiation-burn injury. It was found that: (1) The inhibition of CFU-GM growth in the cultured stromal cell was observed, whether extra CSF existed or not, after the 3~5 th day of combined radiation burn injury. Radiation injury and combined injury resulted in marked depression of it, than the burn injury.(2) Stimulation of the cultured stromal cell in the adherent layer on the growth of granulopoietic progenitors could be achieved.This action was obvious when the extra GM-CSF was absent. (3) Stimulation of stromal cells on CFU-GM formation was observed after all 3 kinds of injuryes.The serious suppression of myelopoiesis in radiation and combined injury showed more obvious stimulation of stromal cells. The results indicated that bone marrow stromal cells played a significant role in reconstruction and recovery of hematopoietic disturbance after combined radiationburn injury.