The aim of this study was to investigate the effects of D-methionine (D-met) on the hematopoietic system injury in irradiated mice. C57BL/6 mice were divided into control group, irradiated group, 300 mg/kg D-met plus irradiation group and 1000 mg/kg D-met plus irradiation group. The control mice received sham irradiation, and the mice in remainder groups were exposed to 7.5 Gy; 1,4,8 Gy and 1 Gy of (137)Cs γ-ray respectively, were used to detect the survival rate, survival rate of bone marrow cells, WBC and its differential counts as well the colony formation ability in irradiated mice, respectively. The D-met was intraperitoneally injected to mice at 30 min before irradiation. The results showed that 300 and 1000 mg/kd D-met did not obviously enhance the survival rate of mice exposed to 7.5 Gy; the 10(-2),10(-3),10(-4) mol/L D-met significantly increased the survival rate of bone marrow cells in mice exposed to 1,4,8 Gy; 300 and 1000 mg/kg D-met even so increased the WBC count of peripheral blood in mice exposed to 1 Gy, but there was no statistical difference as compared with irradiated alone mice, moreover 300 and 1000 mg/kg D-met could obviously promote the colony formation ability of bone marrow cells in irradiated mice, the CFU-GM count was higher than that in 1 Gy irradiated mice (P < 0.05). It is concluded that the D-met can effectively mitigate the marrow cell injury resulted from irradiation, enhance the survival rate of bone marrow cells in irradiated mice, promote the recovery of hematopoietic function from radiation injury in mice.