[en] Objective: To investigate the synergistic effects and mechanism of IL-6 combined with G-CSF on hematological function in irradiated mice. Methods: The numbers of RBC, WBC, PLT and HGB were counted by F-800 apparatus. The numbers of CFU-GM and CFU-S were counted by usual method. The programmed cell death was assayed by agarose electrophoresis. Results: IL-6 combined with G-CSF could accelerate the recovery of peripheral blood, promote the recovery of endogenous CFU-S, and increase the number of bone marrow cells and stimulate the formation of GM-CFU of bone marrow cells. It could raise survival rate of irradiated mice. Conclusion: The synergistic effect of IL-6 combined with G-CSF is better than that of either one. The mechanism of the effect is due to accelerative action on the recovery of residual bone marrow stem cells in irradiated mice. This procedure requires long time, and is not attributed to the inhibitory effect upon programmed cell death of bone marrow cells