In order to investigate radiation effect on the expression of VEGF in murine bone marrow stromal cells, C57BL/6J mice were irradiated to 0, 2.5, 5 and 10Gy by whole body irradiation with ,137,Cs γ−ray. After the bone marrow stromal cells were ex-vivo cultured for 3, 6 or 10d, the mRNA and protein of VEGF in BMSCs were analyzed by RT−PCR and ELISA, respectively. Both of the two indices were up-regulated with the cultural time in the control group (without irradiation). In the 5 and 10Gy group, the expressions of VEGF mRNA in BMSCs increased significantly with the cultural time. Interestingly, in the 5 and 10−Gy group, VEGF concentration in BMSCs cultural media increased on 6d and reduced significantly on 10d after the ex−vivo culture. This is because that total cell numbers of the 10d group had been reduced significantly in comparison to the control group of the same cultural time. These results indicated the expressions of VEGF in BMSCs at mRNA and protein levels increased in each cell after 5 and 10Gy radiation. Up-regulated VEGF might benefit for hematopoietic reconstitution. The association among expression of VEGF, hematopoietic microenvironment and hematopoietic reconstitution deserve further study.