Background: Results from existing studies indicate that different respondent groups’ health state valuations in cost-utility analyses are not equivalent. Objectives: The objectives in our study were to analyse differences in health state valuations among three respondent groups in the context of medical rehabilitation in Germany. Methods: Using the time trade-off (TTO) technique, valuations of EQ-5D-3L health states were obtained from patients with musculoskeletal diseases, healthy volunteers and health care professionals. We used linear mixed models to predict TTO utilities and specified and tested interaction effects. Results: We identified statistically significant (p < 0.05) differences among the three groups in six out of 42 health states. On average, patients’ TTO values were somewhat higher compared with other respondent groups. Most of these differences occurred in severe health states. Mean differences and mean absolute differences were 0.02 and 0.14 for patients vs healthy volunteers and 0.06 and 0.14 for patients vs health care professionals. Furthermore, significant effects among respondents were observed for seven of the 22 possible interactions describing differences between respondent groups. Coefficients associated with significant interaction effects ranged from 0.08 to 0.18 (absolute values). Conclusion: The results of our study suggest that TTO valuations of health states differ depending on the specific respondent group from which valuations are obtained. On average, these differences were small. However, researchers and decision makers should remain aware of these differences when interpreting incremental cost-utility assessments.