In murine chronic graft-versus-host reaction (GVHR), the immune complex composed of antoantibodies has been considered to induce human lupus-like nephritis. We prepared the replica membranes and immunoelectron-microscopic specimens of glomeruli of GVHR mice. The immunoelectron-microscopic examination revealed that immune deposits were noted mainly in the mesangial matrices and subepithelial area. The replica membranes showed various sizes of the deposits in the same portions. Moreover, fine fibrils around the deposits were strongly disrupted. Microfilaments were increased in the cytoplasm of podocytes and endothelial cells were slightly detached from glomerular basement membrane. In this model system, the immune deposits might play an important role in keeping the glomerular integrity.