Five cases of congenital cholesteatoma of the middle ear and mastoid as defined by Derlacki's criteria were encountered over a 14 month period. They make up 5% of all cases of cholesteatoma managed over the same period of time. Three were young children and all presented with unilateral hearing loss. One had associated multiple congenital abnormalities of the external and middle ear. Only in one patient was the diagnosis made on initial otoscopic examination and the remainder diagnosed on CTscan, myringotomy and tympanotomy. All were operated on; three by the intact canal wall technique, one by the canal down technique with mastoid cavity obliteration and one by atticotomy with lateral attic wall reconstruction. One patient required a second stage operation for excision of an extension of disease deep to the superior semicircular canal via the middle cranial fossa approach in order to preserve cochlear function. These five cases illustrate the diagnostic pitfalls of this condition in which silent danger lurks behind an intact tympanic membrane.