Transforming growth factor (TGF)-beta inhibits cell proliferation and stimulates cell differentiation. For the signal transduction of TGF-beta, receptors I and II are required. The present study discloses the immunohistochemical localization of TGF-beta receptors I and II in inflammatory bowel disease. In the normal colon and small intestinal tissue, TGF-beta receptors were expressed in the epithelial cells in the upper crypts. In inflammatory bowel disease, a disordered expression pattern of receptors I and II was observed in the epithelial cells. Fibroblasts in the area of early stage fibrosis were positive for both receptors, while fibroblasts in area of advanced fibrosis lacked immunoreactivity for both receptors. Our study suggests that TGF-beta receptors I and II are important for the initial step of fibrosis.