The most suitable candidates for cochlear implantation (CI) are children with hereditary hearing loss (HL) unless they suffer from some other disability. The commonest cause of hereditary HL in children is mutation 35delG in the Connexin 26 gene. Investigations of 35delG mutation in the connexin 26 gene allow to find children with nonsyndromic HL and to start preparation for early CI, which provides better long term results regarding rehabilitation. The best teaching technique for implantees to achieve spontanious speech is the auditive-verbal method. The commonest cause of HL in adults is cochlear impairment resulting from meningitis or brain trauma. In these cases the most favourable candidates for CI are persons who have acquired speech. In developed countries the long history of CI has resulted in diminishing the number of adult patients in need for CI. In the next few years a similar course of events is expected to take place also in Estonia. In Estonia cochlear implantions are performed in the Ear Clinic of the University of Tartu. The first cochlear implantation was performed in 2000. During 2000–2007 there has been 72 monolateral CI operations. Literature data and our results show that the CI operation has a minor risk of complications. In 2004 audiologic screening of newborns was introduced for early detection and rehabilitation of newborns with HL in Estonia.