OBJECTIVES: To analyze the association between utility, treatment and generic and prostate-specific health related quality of life (HRQoL) among prostate cancer patients.   METHODS:  In this longitudinal cohort study we recruited 201 (≥ 45 yrs) newly diagnosed prostate cancer patients from urology clinics of an urban academic hospital. Participants completed Quality of Wellbeing (QWB-SA), generic (SF-36) and prostate-specific (UCLA-PCI) HRQoL surveys prior to treatment and up to 24 months post-treatment. Clinical and demographic data were obtained via medical chart review and utility scores were computed using QWB-SA. To analyze the relationship between treatment and utility we used linear mixed effects models, after adjusting for covariates. Similar models were used to examine association between generic and prostate-specific HRQoL and utility. RESULTS: Mean baseline utility was comparable between radical prostatectomy (RP) and external beam radiation therapy (EBRT) groups (0.73 vs. 0.69, p=0.1750). Mixed effects models indicated that RP was associated with higher utility at 24 month (OR=1.12, p=0.027), after controlling for covariates.  RP was associated with improved functioning for role physical, role emotional, vitality, mental health and bodily pain and impaired urinary function. Higher scores on generic health subscales were indicative of higher utility. Also, for prostate-specific HRQoL, higher scores on bowl function, sexual function, urinary bother and bowel bother were associated higher utility.  CONCLUSIONS:  Treatment appears to have significant association with post-treatment utility.  Thus, utility assessment provides an important quantitative tool to support patient and physician clinical treatment decision making process of prostate cancer care.