ABSTRACTOsseous fixation of the malleus is discussed as a cause of a combined conductive and sensorineural hearing loss. The characteristic clinical, audiological and histological findings, as well as the aetiology of 66 patients with an idiopathic fixation of the head of the malleus is described. Ninety‐four per cent of these patients had a sensorineural component to their hearing loss far greater than the loss that could be attributed to presbyacusis. Idiopathic fixation of the head of the malleus was the second most common cause of the fixed malleus syndrome in the series of 168 ears operated on in the Ear, Nose and Throat Department of the University of Tübingen between 1972 and 1977. The treatment of choice is to keep the ossicular chain intact. Reconstruction of the disrupted chain is preferred in patients with poorly pneumatized mastoids. Only 15% of the patients with idiopathic fixation showed a significant improvement in their bone‐conduction after sur