Colonic adenocarcinomas evolve through a multistep process from tubular adenomas to invasive adenocarcinomas. Matrix metalloproteinases (MMPs) have been implicated in proteolysis of basement membrane for initiation of metastatic cascade.By immunocytochemical staining, hyperplastic polyps, tubular adenomas, tubovillous adenomas, villous adenomas to adenocarcinomas were systematically examined for the presence of MMP-2 (gelatinase A) and MMP-9 (gelatinase B) and tissue inhibitor of MMP (TIMP)-1 and TIMP-2, respectively.MMP-2 and MMP-9, and TIMP-1 and TIMP-2 were immunolocalized in scattered stromal cells, whereas epithelial cells of normal mucosa and hyperplastic polyps were weakly stained. From tubular adenomas to villous adenomas, immunolocalization of gelatinases and TIMPs showed increasing gradually, and in situ carcinomas showed a definite positive, immunolocalization of gelatinases and TIMPs.Increasing immunolocalization of gelatinases and TIMPs from tubular adenomas to adenocarcinomas coincides with a multistep process of colonic tumorigenesis.