Cochlear implantation is a worldwidely accepted treatment for prelingual or postlingual profound bilateral hearing loss. Experience with these cochlear implantees has demonstrated signlficant benefit with minimal risk. This report focuses upon the intraoperative problems and postorperative complications of cochlear implantation with 22-channel device. Fourty deaf patients in the age range of 2 to 67 have recieved a Nucleus 22 channel cochlear implant from Novermber 1988 to April 1995. Two patient with previous open cavity mastoidectomy required a staged operation for mastoid obliteration using inferior-based flap before cochlear implantation. Ten cases of obliterated scala tympani were encountered and successfully treated by drilling the obliterated bone without major complication. Mobilization of the chorda tympani nerve and removal of the incus made it easy to insert the electrode, especially in the case of narrow posterior, tympanotomy site. Patients with congenital anomalies, such as waardenburg syndrome, Noonan syndrome, and mild Mondini dysplasia, were also implanted without problem. In a case of meningitis, ten active electrodes was inserted because of ossification of the cochlea. There was a case of device failure which was treated with replacement of new device. Several minor postoperative adverse effects such as dizziness, facial or tympanic nerve stimulation were self-limited or disappeared by excluding the appropriate eletrode from stimulation.