A case is reported in which a Nucleus 22 channel intracochlear implant was applied to a Hungarian woman (age 50 yr) with profound deafness associated with osteogenesis imperfecta. Successful intracochlear insertion of the 22 electrodes resulted in a 70 dB hearing improvement at frequencies 250-2000 HZ. Nevertheless, a characteristic facial twitching appeared upon activation of electrodes 9-13. Inactivation of these electrodes abolished the non-acoustic nerve excitation with preservation of acoustic performance. Osteogenesis imperfecta may involve a state of risk for non-acoustic nerve activation in cochlear implant patients possibly resulting from a reduced impedance to current spread by abnormal bone tissue. This, however can be overcome by simple programming manoeuvres.