OBJECTIVES:  Cochlear implantation (CI) is the treatment of choice for patients with severe to profound sensorineural hearing loss; no definite evidence exists concerning benefits for prelingually deafened adult. The study aims to estimate efficacy of CI in terms of gains in speech perception abilities, subjective benefits and quality of life for prelingually deafened adults. METHODS:  30 oral language user patients with hearing aids consecutively submitted to unilateral CI at the ENT Unit of the University of Pisa (Italy) from 1999 to 2011 have been enrolled. Case Report Forms were submitted including the Abbreviated Profile Of Hearing Aid Benefit (APHAB) and the Short Form-36 Health Survey (SF36) questionnaires. Comparison between pre and post CI patients data has been performed, including the Wilcoxon matched-pairs signed-ranks test. Using quantile regression, relationship between post implantation open-set speech recognition score and patients characteristics has been investigated. RESULTS:  After CI statistically significative improvements have been recorded in speech perception and in ability to have telephone conversations, as well as in ease of communication, background noise, reverberation and aversiveness. The norm-based scores of the SF36 revealed a significative improvement after CI as compared to the before situation in terms of general health (median score before 57,9; IQR: 50,9-61,7 versus after 60,3; IQR: 54,6-61,7, p=0,003), social functioning (46,3; IQR: 35,4-57,2 versus 49,0; IQR: 40,9-57,1, p=0,026) and mental health (45,9; IQR: 39,1-55,0 versus 52,7; IQR: 45,9-55,0, p=0,004). The patient’s own quality of life perception after CI was very similar to that of the normative sample of Italian healthy subjects. Association between post implantation open-set speech recognition score and progression of hearing loss was found (p < 0,05). CONCLUSIONS:  CI is an option that may be effective for prelingually deafened adult patients in terms of improvement of speech perception abilities, quality of life and patients’ own perception of their disability.