Patients with Treacher Collins syndrome have severe middle ear malformations that render operation difficult. We have evaluated 43 patients with Treacher Collins syndrome, on whom only 11 were operated. Computed tomography, the single most important study done preoperatively, routinely showed an underdeveloped temporal bone with islands of bone marrow and absent mastoid pneumatization. The middle ear space was often underdeveloped. Ossicular dysjunction was often noted in which the fused malleus/incus remnant was found 3 to 4 mm distant to the stapes. A common finding was severe dysplasia of the stapes-facial nerve complex that often made the middle ear malformation uncorrectable. Hearing results were much less predictable than in patients with isolated atresia/stenosis of the ear.