BALB/c and C57BL/6 mice are purebred congenic mouse strains with different major and minor histocompatibility antigens (MHC-I and MHC-II) and are available for graft rejection studies. Allogeneic BMT models using C57BL/6 and BALB/c mice have been established by different laboratories worldwide, but BALB/c and TLR4 knockout mouse models of GVHD have rarely been reported. Due to different GVHD conditions in mouse models resulting from different mouse origins, rearing conditions, and radioactive sources, it is necessary to establish a TLR4 knockout mouse model suitable for local experimental conditions. Our laboratory established a TLR4 knockout (TLR4-/-) mouse GVHD model for allogeneic BMT between TLR4+/+ and BALB/c mice or TLR4-/- and BALB/c mice9. Among these mice, BALB/c mice have strong productivity and a long idiophase but are sensitive to carcinogenic factors and radiation. TLR4 knockout (TLR4-/-) mice are on the same background as C57BL/6 mice (TLR4+/+). We found that TLR4 inactivation attenuated GVHD, but the relationship between TLR4 and the development of GVHD is still unknown.