We aimed to evaluate the subcutaneous tissue reaction to a newly developed adhesive silicone denture relining material, SG, (Neo Dental Chemical Products Co., Ltd. Tokyo, Japan). We embedded the experimental material SG and another existing control material, Roeko Seal (RS), in the dorsal area of 22 male ddY mice. One week and 12 weeks after the embedding, the tissues surrounding the embedded materials were removed and a histopathological examination was performed. The results demonstrate that the basic histopathological aspects are the formation of granulation tissue and the change of the tissue to fibrous capsule over time. The results suggests that the newly-developed SG is safe as compared with the control RS, whose composition is similar.