['To assess the effect of the use of cochlear implants (CI) on the health status of postlingually deaf adults.', 'Participants comprised 45 postlingually deaf adult multichannel CI users and 46 deaf candidates on the waiting list for a CI. The latter group acted as control subjects to corroborate the validity of retrospective completion of the questionnaires by the CI recipients. Three HRQOL instruments were used: a) a specially developed CI questionnaire (NCIQ); b) a generic HRQOL questionnaire (SF-36); and c) a health-state classification system (HUI-2) suited to estimate single preference scores.', 'Retrospectively estimated pre-implant scores in the CI user group corresponded very well with the scores in the control group. Postimplant scores in the CI users were substantially higher in all six domains (p < .001) of the NCIQ than the scores in the control group. Effects due to a CI were also observed with the SF-36 in five of the seven domains (p < .01). Statistically significant differences between the two groups (p = .001) were observed in two of the six domains of the HUI-2.'] Do the effect of cochlear implant use in postlingually deaf adults?