Background: The side effect profile of androgen deprivation (ADT) warrants exploration of alternative options for elderly patients with systemic PCa. In phase 2 trials, the combination of anti-androgen and 5 alpha reductase inhibitor (PAB) demonstrated efficacy with low morbidity in the fit population. The objective of this retrospective study was to evaluate the characteristics and outcomes of elderly patients treated with PAB in lieu of ADT. Methods: We reviewed records of patients ≥65 yrs who received PAB in the geriatric oncology program from 2007-2012. Patients were evaluated with a validated comprehensive geriatric assessment (CGA) prior to PAB. Descriptive statistics were used to evaluate PAB type, characteristics of patients and their cancers, as well as PCa –specific and overall outcomes Results: Twenty-one asymptomatic PCa patients received PAB (bicalutamide alone-57%, or bicalutamide and finasteride-43%) in lieu of ADT. Indications for treatment were metastatic disease (53%) or biochemical relapse with PSA doubling time≤ 6 months (47%). Median age at the initiation of PAB was 86 years (range 65-94) and 76 % had ECOG PS≥ 2. By CGA, 57 % were vulnerable, 33% frail and 10% fit. 76% had contraindications for standard ADT (e.g., dementia, falls, etc.); the rest declined ADT due to concern about adverse effects (AE). The median PSA at PAB initiation was 14.78 (range 0.9-165.8). PSA nadir (i.e. 1^st of 3 consecutive PSA levels where values were within 90%) was reached in 57% of patients at the time of analysis with the remainder demonstrating a continuing decline. Median PSA at nadir was 0.86(range 0.02-11.24). The median follow up time was 11 months (range 1-30). The median time to PSA nadir was 5 months; (range 1-19). PSA nadir was maintained for median of 10.5 months (range 3-24).The median % decline in PSA was 92 % (range 13-99%).No patients reported AE or required treatment interruption. Two fit patients of the 4 who progressed on PAB responded to subsequent ADT. Conclusions: These results provide evidence that PAB is feasible, active and well tolerated in patients for whom ADT may be contraindicated. A prospective phase II study for an older vulnerable patient population is planned.