The Tullio phenomenon is defined as an acoustically inducible vestibular disorder that was first described in 1929. In an animal experiment Tullio provoked acoustic oscillations at the labyrinth followed by signs of imbalance. In the literature this phenomenon can be found in healthy but sensitive persons as well as in patients with Meniere's disease and patients with lesions between the stapes, footplate and the membranous labyrinth caused by fractures, stapes dislocations, labyrinthitis or perilymphatic fistulas. In this case report a patient complained about vertigo after cochlear implantation provoked by acoustical stimulation at a sound pressure level above 90 dB independent of the cochlear implant (CI). During tympanoscopy we found scar tissue surrounding the ossicles after CI. After disconnecting the ossicular chain no vertigo or nystagmus could be provoked. After CI regular ENT examinations and appropriate explorations of postoperative complaints are necessary. Vertigo especially requires very careful diagnostic procedures.