Two cases are presented of bilateral conductive deafness in siblings. An initial presumptive diagnosis of otosclerosis was made in the first case, that of a nine-year-old girl with a bilateral hearing loss of 45 dB. Exploratory tympanotomy revealed normal ossicles but the stapedius ‘tendon’ was found to be a solid bony bar fixing the stapes. Division of the ‘tendon’ resulted in normal ossicular mobility and return of hearing with closure of the air-bone gap. Identical ossification was found in her other ear, and some years later in both ears of one of her brothers. Similar surgery restored hearing successfully in each case. An acquired aetiology has been proposed in one of the three previously reported cases; this report, however, suggests the congenital nature of the anomaly. No previous cases have been described occurring in siblings.