Purpose: In cost-utility analysis, outcomes are usually measured in terms of quality-adjusted life years, where length of life is adjusted by levels of health-related quality of life (HRQoL) using a single value, known as a health state utility value (HSUV). This study explores the HSUVs of parents of children with a serious illness admitted within three hospital departments (cardiology, oncology and paediatric intensive care) across four time points, compares HSUVs with Australian population norms and examines predictors of parental HSUVs. Methods: Data were obtained from the Take a Breath study, where parental HSUVs were measured using the Assessment of Quality of Life-8 Dimensions (AQoL-8D). Descriptive statistics and t-tests compared the AQoL-8D scores with population norms, while repeated measures ANOVA was used to compare parental HSUVs of children treated across illness groups over time. Regression analysis was performed to determine predictors of parental HSUVs. Results: Parental HSUVs were not significantly different from the general Australian population norms (p = 0.939), as measured by the AQoL-8D. However, statistically significant differences were observed in the psychosocial super-dimension (p < 0.01) and in all eight AQoL-8D dimensions, except for senses and self-worth. No significant differences were observed across illness groups. Parental HSUVs were associated with psychosocial risk factors of trait anxiety (p < 0.001), depression (p < 0.001) and family beliefs (p = 0.024). Conclusion: Having a child with a severe illness has an impact on the psychosocial aspects of parental HRQoL regardless of the type of illness. Psychosocial health factors of trait anxiety, depression and family beliefs were important predictors of parental HSUV.