Pericryptal myofibroblasts (PMFs) are thought to be involved in the production of the basement membrane (BM) of the colonic epithelium. To clarify the involvement of PMFs in the formation of the BM during the growth of colon cancer, we conducted an immunohistological study of tumor specimens from 85 patients with colorectal epithelial tumor to detect the presence of PMFs. The tumor specimens were classified as adenoma with low-grade dysplasia, adenoma with high-grade dysplasia, or colon cancer. PMFs were detected in 66.6% of the specimens from patients with adenoma with low-grade dysplasia; 20% of specimens of adenoma with high-grade dysplasia; and 3.2% of specimens of colon cancer. As the degree of dysplasia of the tumor increased, the probability that PMFs existed decreased. We also tested 49 of the tumor specimens for the presence of laminin, a component of the BM, and found that in most of these 49 cases, the BM and PMFs co-existed. This provides further evidence that PMFs are involved in the production of the BM. These findings are important in gaining an understanding of the cause and growth of colorectal epithelial tumors.