Recent studies demonstrated that a single guanine insertion polymorphism in a matrix metalloprotease-1 promoter created an Ets binding site and affected the elevation of the transcriptional level of matrix metalloproteinase-1 (MMP-1). Furthermore, in tumor cell lines derived from melanoma and breast cancer, the incidence of the 2G / 2G genotype was significantly higher than that in the normal population. To evaluate the contribution of this polymorphism in endometrial carcinomas, we genotyped 100 endometrial carcinomas and then analyzed immunoexpression of MMP-1 in these carcinomas. We found that endometrial carcinoma patients showed a significantly higher rate of 1G / 2G or 2G / 2G genotype than control individuals, and that tumors containing the 2G allele(a) expressed MMP-1 protein more frequently than those with 1G / 1G genotype. Therefore, the single nucleotide polymorphism at the MMP-1 promoter affected the expression level of the MMP-1 protein, which may result in the association with more aggressive character in endometrial carcinoma. Our result suggests that the presence of 2G polymorphism at the MMP-1 promoter may be one of the risk factors for the development and / or progression of endometrial carcinoma.