The authors evaluate histological findings by light microscopy in 17 temporal bones of foetuses with genetically confirmed Down syndrome (trisomy of the 21st chromosome). In the area of the external or middle ear changes were diagnosed in five (29 %) temporal bones, in the inner ear in three (18 %) temporal bones. As to pathological findings, retardation of development was involved, abnormalities of the ossicles in the middle ear and of the auditory tube. A very rare finding in one foetus is bilateral Mondini dysplasia of the cochler. Based on the presented investigation and findings in the literature it is not possible to assess typical changes of the vestibular organ in patients with Down syndrome. In clinical practice, however, in these patients possible affection of hearing must be considered.

        Key words: temporal bone, histology, trisomy 21, Down syndrome.