Petrosal cholesteatomas are rare lesions, which may be congenital or acquired in nature. We report an exceptional case occurring in a seven-year old girl who presented with a unilateral conductive hearing loss, despite normal tympanic membrane appearance. Early diagnosis was facilitated by computed tomography (CT) scanning. Although this case satisfied the criteria for congenital cholesteatoma, it is likely that the petrous apex was secondarily involved. Complete cholesteatoma removal was accomplished using a transtemporal supralabyrinthine approach, which allowed for hearing preservation, while avoiding the morbidity associated with a craniotomy. The present case constitutes the youngest case of petrosal cholesteatoma reported. We suggest that a lower threshold for the use of CT scanning in unilateral conductive hearing loss may allow for the earlier detection of more cases of petrosal cholesteatomas, as well as facilitating their removal using more limited approaches associated with less morbidity.