This paper discusses a rare complication of an intracochlear misdirection of the electrode of a cochlear implant in a 55-year-old male. The patient received a cochlear implant using the mastoid-saving surgical approach. Intraoperative measurements showed impedance and NRT reactions suggesting a reasonable function of the inner ear and the implant. Postoperatively our patient suffered from passing vertigo. Postoperative CT scans revealed a misdirection implantation of the cochlear implant into the vestibular part of the inner ear. A deformed implant was removed and a reimplantation was successfully performed after enlarging and reshaping the cochleostomy. Our patient now enjoys all the benefits of an optimal functioning cochlear implant. Intracochlear misdirection of the electrode can occur even when intraoperative measurements seem to be normal. When a patient suffers from unexplained vertigo after cochlear implantation with a poor function of the implant a misdirection of the active electrode must be considered. New high resolution peroperative three-dimensional imaging techniques can probably help to avoid such insertion failures.