4577 Background: It is generally acknowledged that men who are most likely to derive benefit from therapy for prostate cancer are those with a life expectancy of greater than 10 years. We examined the patterns of primary treatment for prostate cancer in men ≥75 years of age who would have a life expectancy of approximately 10 years. Methods: We examined data from the multi-institutional CaPSURE database on type of primary therapy received for prostate cancer in men < and ≥75 years. Primary therapy was defined as watchful waiting (WW), radical prostatectomy (RP), brachytherapy (BT), BT plus external beam radiotherapy (BT+EBRT), EBRT or primary androgen deprivation therapy (PADT). Chi square tests and multinomial logistic regression analysis were performed to identify predictors of type of primary therapy. Results: The median age of the entire population (n = 10,764) was 67 years and 18% of the dataset were patients ≥75 years. A greater proportion of patients ≥75 years were white, single, had multiple co-morbidities, had low income and low education levels and were classified as high risk (43% vs. 25%) compared to those <75 years. Men ≥75 years were more likely to have received EBRT, PADT or WW (all p < .01). In a multivariate analysis adjusted for socio-demographic factors, diagnostic risk category, and number of co-morbidities at diagnosis, patients ≥75 years were less likely to be managed with primary therapy than with WW regardless of risk category or level of co-morbidity: BT (OR 0.21, 95%CI 0.15–0.31), BT/EBRT (OR 0.21, 95%CI 0.16–0.28), EBRT (OR 0.29, 95%CI 0.22–0.37), PADT (OR 0.64, 95%CI 0.51–0.81), and RP (OR 0.01, 95%CI 0.01–0.02). Conclusions: Older patients are far more likely to received WW as primary therapy regardless of burden of co-morbidity or risk level of primary cancer. A more tailored approach to prostate cancer therapy taking into account co-morbidity and functional level to decide primary therapy may be more appropriate in elderly men. Well selected older patients with high risk disease, particularly those with low co-morbidity levels, may derive survival benefit from primary therapy other than WW. [Table: see text]