A case is presented where the authors carried out a cochlear implantation on a girl whose deafness was induced by cytostatic agents. The normally hearing child was diagnosed with Langerhans cell histiocytosis at the age of 3 years and received polychemotherapy for almost 2 years. By her 5th year, she started to develop a bilateral, progressive sensorineural hearing loss, necessitating a hearing aid in both ears. While her histiocytosis was cured, her hearing ultimately deteriorated to total deafness on the right and profound hearing loss on the left ear. After 3 years, her hearing aids no longer provided adequate hearing for the postlingually deafened girl. At the age of 14, a cochlear implantation was performed on her right ear with excellent results.