Purpose The Minimal Clinically Important Difference (MCID) is an evolving concept that relates some change in the score of a health status instrument to some external reference of an important change in health status. When the external reference of clinically important change incorporates the preferences of the patient in management decisions, measurement of the MCID may provide a method to link the change in score of a health status instrument and the utility. Methods The MCID was determined for the Carpal Tunnel Syndrome (CTS) disease specific instrument by measuring the change in the score of the instrument caused by injection of the carpal tunnel in a sample of 28 patients. The management of the patient was based on the preference of the patient for observation, repeat injection, further testing, or treatment. A blinded observer rated the patients' response to injection as satisfactory or unsatisfactory based on review of the management of the patient. The best cut-off for the MCID was determined using Receiver Operator Characteristic (ROC) curves. Second, we administered the CTS disease specific instrument to 68 patients to assess their disease severity and measured their utility for CTS using the Standard Gamble (SG). Third, we measured the utility for three levels of severity of CTS using the SG in a population of 90 surrogates. We created three levels of health status descriptions from three distinct levels of disease severity that were highly endorsed by patients in step two. Results The MCID for the carpal tunnel instrument after injection of the carpal tunnel was an improvement of the symptom severity score of 1.04 on a scale of 0 to 5, with 5 representing the most severe CTS. In the patient population, a regression equation linking utility and symptom severity was determined. The change in utility corresponding to the MCID was 0.01. In the surrogate population, the change in utility corresponding to MCID was .0082. Conclusion When the MCID is measured in a manner that incorporates patient preference it may be possible to estimate the utility that corresponds to a meaningful difference in a patient's health status. This study provides evidence that utility differences of 0.01 are important in this problem.