OBJECTIVES: Health state utilities are essential for health economic analysis. This study assesses the utilities for different health states in breast cancer (BC ), compares different HRQoL instruments and explores factors associated with poor HRQoL. METHODS: An observational cross-sectional study among BC patients in the Hospital District of Helsinki and Uusimaa was carried out between September 2009 and April 2011. A total of 778 BC patients (aged 31­-90) assessed their HRQoL with the generic 15D and EQ-5D+VAS and the cancer specific EORTC-QLQ C30 HRQoL questionnaires. Patients were divided into five mutually exclusive groups based on disease state: baseline before treatment (n=52), 1st year of remission after diagnosis or recurrence (n=128), 2nd or following years after remission (n=405), metastatic disease (n=177) and terminal care (n=16). Linear stepwise regression analysis was used to evaluate the association between the VAS-score and clinical and demographic factors as well as the EORTC symptom and functioning scale scores. RESULTS: The mean (± SD) utility values with 15D were for baseline patients 0.896±0.083, 1st year of remission 0.901±0.80, following years after remission 0.884±0.103, metastatic disease 0.825±0.113 and for palliative patients 0.756±0.110 and with EQ-5D 0.818±0.228, 0.860±0.178, 0.843±0.189, 0.746±0.251, 0.514±0.300, respectively. The difference between the instruments was consistent in all states of the disease. In regression analysis, higher EORTC QLQ-C30 scores for social, role and emotional functioning were associated with improved HRQoL. However, the most important explanatory variable was higher education. CONCLUSIONS: The utility scores were highest at 1st year of remission and deteriorated in the more advanced states of the disease. The 15D provided higher utility values than the EQ-5D. The choice of the HRQoL instrument has a significant effect on the utility values. Regression analysis showed that functioning has more impact on HRQoL than symptoms or clinical and demographic parameters except for education.