The economic evaluation of health care technologies employs a standard economic approach based on preferences to provide utility information. Previous studies have used happiness rather than preferences to weight health states using general population data. However, these data may not reflect the full range and scope of health and happiness experienced by patients. This paper applies a similar approach to a large patient sample (N = 15,184) from a hospital in Wales, UK collected between 2002 and 2004. Logit regression models were used to assess the relationship between happiness and the health state classifications of two measures, the EQ-5D and the SF-6D. The results suggest a different weighting across dimensions to that from preference elicitation techniques such as time trade-off and standard gamble. While mental health (depression and anxiety), vitality and social functioning were found to have a large significant association with the patients' own happiness assessment, pain was less so and physical health had no association. ► We tested whether subjective well-being could be used to weight health states in patient data. ► In contrast to preferences, mental health and vitality were ranked more highly than physical functioning and pain. ► This mirrored findings in studies using general population data but with stronger effects than those reported previously.