This paper reports a rare clinical observation of congenital malformation of the internal and middle ear diagnosed with the help of functional multispiral computed tomography (fMSCT). The patient presenting with conductive hearing loss was suspected to have otosclerosis. However, the use of fMSCT made it possible to arrive at a more precise diagnosis, that is congenital malformation of the internal and middle ear that clinically manifested itself as the conductive loss of hearing. It was decided to refrain from the surgical intervention: first, because its efficacy in this case was considered to be doubtful and second, it was fraught with the high risk of development of postoperative complications.