We report a case of a 23-year-old man with unilateral hearing loss since childhood. Otoscopic examination was entirely normal. Audiometric testing showed a conductive hearing loss in his left ear, with an average pure-tone audiometry of air conduction of 80 dB and a maximum air-bone gap of 60 dB at 1,000 Hz. Tuning fork tests confirmed conductive hearing loss. Tympanometry showed increased compliance in the left ear and an absent ipsilateral stapedial reflex. Temporal bone imaging using contiguous 1-mm sections of the left temporal bone revealed an absence of the long process of the incus and a possible absence of stapes suprastructure (Fig. 1, C and D). The facial nerve had a normal course through the middle ear and mastoid (Fig. 1, A and B). During surgery, we found that stapes superstructure and long process of incus were absent, and in their place, there was a fibrous tissue ( Fig. 2A). There was also a mobile footplate and a normal chorda tympani and facial nerve (Fig. 2B). Incus body was fixed to a normal malleus as shown by a preoperative computed tomographic scan FIG. 1. Temporal bone computed tomographic scan, left ear, axial view. A and B, Normal facial nerve (white arrowhead) in the middle ear. Incudomalleolar joint can be seen. C and D, View of the vestibule at the oval window level (asterisk). The white arrow indicates fibrous tissue instead of long process of the incus.