ABSTRACTBilateral conductive deafness is common in mandibulofacial dysostosis with or without atresia of the external auditory meatus. This deafness is due to a wide range of deformities of the ossicular chain associated with a characteristic reduction in the size of the middle ear cavity. The attic and antrum are particularly affected and usually have a slit‐like appearance on coronal section tomograms. The inner ear is essentially normal. The tomographic appearances of 44 ears from 22 patients with mandibulofacial dysostosis are described as well as the operative findings in 14. These were correlated with induced ear deformities in an animal model that had features characteristic of human mandibulofacial dysostosis. A review of the findings in the animal model suggests a very close correspondence with the human ear anomalies described at radiological investigation, operation and post‐mortem examination. The lesions are largely symmetrical and this, with the characteristic slit attic, helps to differentiate mandibulofacial dysostosis from lesions with different aetiology but similar features such as facial microsomia. The prospects for surgical correction of the deafness in mandibulofacial dysostosis range from very good in mild cases with ossicular discontinuity, to poor where there is severe atresia. The importance of tomograms at an early age is stres