Objective To investigate the role of matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-2 (TIMP-2) in the pathogenesis of endometriosis. Methods Immunohistochemical S-P method was employed to detect the expression of MMP-2 and TIMP-2 in the ectopic tissues and eutopic endometrium of 22 patients with endometriosis and 20 normal controls. Results The expression of MMP-2 in glandular cells was significantly higher than those of uterine endometrium from women with and without endometriosis (P0.05). The expressions of MMP-2 and TIMP-2 were not related to the degree of endometriosis. Conclusion The increased expression of MMP-2 and the decreased expression of TIMP-2 in the ectopic endometriotic tissues result in the higher ratio of MMP-2/TIMP-2 that can make ectopic endometrial tissues have a greater capacity to invade and play an important role in the pathogenesis of endometriosis.