Purpose: Decision analysts have established that patients' utilities regarding treatment outcomes are critical to determining how prostate cancer should be treated. Prostate cancer treatment outcomes also have a substantial impact on spouses as well as the patients themselves. However, little research examines men's relationships and their spouse's perceptions to the utility of the prostate cancer treatment outcomes. Methods: Fifty-four men being treated for prostate cancer and their wives participated in structured interviews. Standardized measures focused on relationship qualities (depth, conflict, and social support by Pierce et al., 1991), decision satisfaction (uncertainty, factors contributing to uncertainty, and effectiveness by O'Connor, 1995), coping with cancer (approach and avoidance strategies by Merluzzi & Sanchez, 1997), and prostate treatment outcome utility (Krahn et al., 2000). Patients responded to each of the scales for themselves; with the exception of relationship qualities, patients' spouses also responded to each of the scales evaluating the patient's decision, coping and treatment outcome. Spouses were also asked about their own perceptions of relationship qualities and their coping with their husband's cancer. The frequencies and importance of ten health domains describing outcomes of prostate cancer treatment were used to calculate utility scores. Results: Although wives overestimated the frequency of their husbands' problems and the negative utility of those outcomes, correlations established strong associations between husbands' and wives' perceptions. Qualities of the marital relationship that were associated with patients' utility scores included: wives' reported marital conflict (p<.0001), support (p=.003) and satisfaction (p=.004) as well as the patients' own perceptions of marital conflict (p=.048). Discrepancies in patients' utilities and t wives' perceptions of the patients' utilities were related to the wives' perception of the depth of their relationship (p=.015) and patients' perceptions of marital conflict (p=.01). Conclusions: Overall, patients' spouses' perception of the quality of the marital relationship was more predictive of utility scores and their differences than the patients'. In particular, greater marital conflict was associated with patients' and spouses' increased negative utility scores and the differences in the couples' utility scores. Because men's wives are not only likely to accompany men to their medical appointments but also provide significant support when their husbands are diagnosed and treated for prostate cancer, these findings have important implications for shared decision making.