The Nijmegen Cochlear Implant Questionnaire (NCIQ) is a specific and quantifiable self-assessment health-related quality of life (QoL) questionnaire. It was developed to determine the subjective benefits of a cochlear implant (CI). The present study aimed to determine the validity and reliability of the NCIQ in Spanish. Seventy-six adult, Spanish speaking, CI users and 28 control subjects answered the NCIQ. Reliability of the questionnaire was determined using Cronbach's α coefficient and the validity established using Pearson's correlation coefficient. All questionnaire respondents performed significantly better in all sub-domains with a cochlear implant than before cochlear implantation. The Cronbach's α score exceeded 0.70 in most sub-domains and the total score. The objective measures: bisyllables tested without lip-reading and with masking; and bisyllables, tested without lip-reading and without masking were correlated with the sub-domain 'advanced sound perception'. To determine health-related QoL the NCIQ in Spanish is a reliable self-assessment questionnaire and a valuable instrument in determining the subjective benefit of a CI.