Chronic otitis media with cholestratoma is an inflammatory disease clinically characterized by bone destruction but the mechanisms of this destruction is not clearly known yet. There are various opinion about its mechanism. In recent years, various cytokines which secreted by activated macrophage are demonstrated by immunohistochemical method or enzyme-linked immuno-sorbent assay. These cytokines are tumor necrosis factor-α(TNF-α), interleukin-1α(IL-1α) and parathyroid hormone-related protein(PTHrP). The production of TNF-α by human macrophage in vitro was studied by many authors. We are interested in TNF-α. The epithelia of cholesteatoma tissue and normal external auditory canal skin were obtained from patients with cholesteatoma at ear surgery. Tissues were immediately frozen to -70 and 6 micrometer frozen sections were prepared and were stained by the indirect immunofluorescence method. Intensity of staining in cholesteatoma epitherium was more stronger than in nomal external auditory canal skin tissue. Cell culture was done. In the western blotting assay, a rather strong band was detected at choleateatoma epithelium. We firmly believe that the TNF-α of cholestratomatous keratinocytes is an important factor in the mechanism of bone destruction in cholesteatoma.