Objectives: Cochlear implantation can restore access to sound and speech understanding in subjects with substantial hearing loss where acoustic hearing aids do not. The Health Utilities Index Mark III (HUI3) is commonly used to measure health utility across all types of intervention and is sensitive to changes in hearing. In the current study we analysed for factors predicting clinically important gains in HUI3 scores in adult Nucleus cochlear implant recipients, implanted in a single centre. Design: Retrospective analysis of data collected in an observational study. Demographic and other baseline parameters were analysed for their association with gains in HUI3 scores. Participants: One-hundred and thirty-seven adult recipients of Nucleus cochlear implants who had at least one-year follow-up. Main Outcome Measures: HUI3 scores and speech, spatial, quality (SSQ) scale scores were collected at baseline before device activation and one-year after. Difference scores were computed. Clinically important gain was defined as 0.1 point on the HUI3 scale. Results: Baseline telephone use and baseline HUI3 hearing, speech and emotion attribute levels were significantly associated with clinically important gains in HUI3 scores. However, SSQ scores increased significantly with or without clinically important gains in HUI3 scores. Conclusion: Those subjects who were unable to use the telephone prior to cochlear implantation were one-and-a-half times more likely to obtain a clinically important gain in health utility. Those subjects who were unhappy, or experienced difficulties communicating with strangers were twice or more likely to obtain a clinically important gain in HUI3 scores compared to those who did not.