The histopathological observations were done about biopsy specimens obtained during surgery of middle ear and/or mastoid antrum from 33 cases of cholesteatoma. The results were as following : 1) The epithelial layer of cholesteatoma consisted of keratinizing stratified squamous epithelium with keratin accumulation, and it was subclassified as keratin layer, granular layer, prickle cell layer, and basal layer. The intercellular bridge was found. 2) Just below epithelial layer, the papillary layer of subepithelial space was found and the fibroblasts running parallel to rete peg were found. 3) The subepithelial space showed various stages by the degree of the inflammatory reaction from microabscess to dense fibrous connective tissue consisting of collagen fiber. 4) The cholesterol granuloma was found at the specimen of cholesteatoma and it showed cholesterol clefts, fibroblasts, foreign body type multinucleated giant cells, hemorrhage, neovasculization. 5) The aural polyp showed stratified squamous epithelium and subepithelial space with inflammatory cells infiltration of plasma cell and lymphocyte.