Materials/Methods: A time trade-off instrument was developed to directly elicit preferences from patients on the trial. The elicitation instrument included a written script, data collection form, and visual aid to facilitate the understanding of trading time. The instrument was administered face-to-face during patient clinic visits at baseline, 1, 2, 4, 6 months, and every 3 months thereafter. Patients traded time based on their preference for a fixed amount of time in their current state of health (reference period) versus a reduced amount of time in optimal health. The elicitation procedure was framed using three different reference periods - 10-year, 5-year, and 1-year. Mean utilities were evaluated between treatment groups (SRS vs. SRS WBRT), demographic variables, and within subjects over time. Results: The mean age of patients in the trial was 61 years (range 32‐80). Twenty-four patients received SRS and 17 received SRS and WBRT. The majority of patients had lung cancer as their primary tumor (61%) and most had only one metastatic lesion to the brain (68.3%). Of the 43 patients enrolled in the trial, 41 participated in the elicitation exercise. The mean baseline utility over all reference periods was 0.87 and the mean 6-month follow-up utility over all reference periods was 0.82. There were no significant differences in mean utilities from baseline to six-month follow-up between treatment groups or demographic variables. There were significant differences in mean utilities for all patients across different reference periods. Utilities were significantly higher when using the1yr reference period (1yr reference period mean 0.91, 5yr reference period mean 0.88, 10yr reference period mean 0.84; adj. F 4.2, p 0.049). The same effect was observed for one-month follow-up utilities (1yr reference period mean 0.97, 5yr reference period mean 0.87, 10yr reference period mean 0.85; adj. F 5.3, p 0.03). At the one-month follow-up, mean utilities were significantly higher for those receiving SRS without WBRT using the 1yr reference period (SRS group mean 1.0; SRSWBRT group mean 0.93; F 4.7, p 0.042). At the two-month follow-up, mean utilities were significantly higher for patients having their primary tumor site in the lung versus all other primary tumor sites (lung primary mean utilities 0.93, other primary mean utilities 0.71; F 5.0, p 0.037). Conclusions: Utilities for patients in this trial were relatively stable and remained high suggesting reasonable preference for their current health state at the time of elicitation. Most patients did not trade time in their current health state for less time in a more optimal health state when the trade-off was presented with a short 1-year reference period. This utility analysis will provide data needed to perform cost-utility analysis of SRS vs. SRS and WBRT in the future.