OBJECTIVE: To predict Health State Values (HSV) from health-related quality of life (HRQL) assessments could, if possible, be a fruitful way to use HRQL values for health-economic evaluations. With this in mind, we investigated to what degree values from the EuroQol instrument, the EQ-5D index, and the EQ-VAS visual analog scale value, could be predicted using HRQL measures for patients with respiratory diseases. METHODS: Data from two surveys of patients with respiratory disease were used for this evaluation. The first data set was from 206 patients in Hungary suffering from asthma, and the other was from 120 patients in the northern part of Sweden with COPD. Both surveys included patients with different severities of the diseases. The HRQL instruments used in both surveys were the SF-36, a generic instrument, and St George’s Respiratory Questionnaire (SGRQ), a disease-specific instrument. The two data sets were analyzed separately using a multiple logistic regression model in a stepwise manner to predict EQ-5D and EQ-VAS from the 8 domains of SF-36 and the 3 domains of SGRQ, after transformation of EQ-5D and EQ-VAS to a 0-1 range. RESULTS: The amount of variation in both the EQ-5D and EQ-VAS that could be explained from the combined HRQL measures was at most 56%. EQ-5D had larger values than EQ-VAS. Using SF-36 domains only as predictors gave marginally lower values. The two domains from SF-36 with best predictability explained about 90% of the reduction achieved with all 11 domains together from the two HRQL-measures, indicating correlation between the different domains. CONCLUSION: Values for EQ-5D and EQ-VAS predicted from SF-36 and SGRQ have moderate precision and should be used cautiously.