The acute effects of variable dos rates to total body irradiation (TBI) were investigated with 600 cgy of single exposure in the mice as a preclinical model. Total 80 mice (ICR) were used. Twenty of which served as controls, receiving no irradiation. All irradiated mice showed a universal decline in their weight and white blood cell count. The degree of weight loss and leukopenia were similar at 3 different dos rate but slightly prominent with 15 cgy/minute group. The degree of recovery among the groups showed no dose rate dependence. Our results suggest that TBI with 15 cgy/minute may be applicable for clinical therapy with careful evaluation of patient's condition.