Malleus head fixation and otosclerosis causing conductive hearing loss are often difficult to differentiate by clinical features. Up to now exploratory anterior tympanotomy was necessary to distinguish these pathologies. The case of a 22-year-old male suffering from conductive hearing loss of the right ear is presented. Otosclerosis was suspected and high-resolution CT scanning of the petrous bone was performed. The diagnosis was confirmed radiologically by the detection of an isolated malleus head fixation. Instead of explorative anterior tympanotomy, radiological and audiological controls were combined for the follow-up.