Cholesterol granuloma is not a clinically or pathologically independent entity. It may develop in any portion of the pneumatic system of the temporal bone and can be associated with a variety of middle ear disorders. Three factors are considered to play an important role in its development;1) interference with drainage 2) hemorrhage and 3) obstruction of ventilation. We reviewed 20 cases of cholesterol granuloma in the temporal bone by analysing findings of myringoscopy, temporal bone CT and/or MRI and operation, and concluded that cholesterol granuloma appeared clinically in three forms;1) in association with chronic otitis media, especially cholesteatoma 2) idiopathic blue eardrum 3) localized lesion in the middle ear, mastoid antrum, external auditory canal and petrous apex.