Epidemiologic and experimental evidence suggests the effectiveness of androgen deprivation therapy (ADT) in prostate cancer (CaP) management. Although ADT has been increasingly used as mono-therapy in CaP, the survival benefit of ADT remains unclear. We examined the effectiveness of ADT in prolonging survival in a community-based cohort of 64 475 older men diagnosed with locoregional CaP, in 1992-1999 with last follow-up through December 2002, in 11 Surveillance Epidemiology and End Results (SEER) registries. The effect of ADT on survival was assessed using Kaplan-Meier's method, log-rank test and Cox proportional hazards. After adjustment for propensity to receive ADT, the ADT and non-ADT groups were significantly different in the distribution of covariates except for comorbidity score and SEER registries. The crude overall mortality was significantly higher in cases with ADT compared with cases that received no ADT, hazard ratio (HR=1.54; 95% CI=1.50-1.58). However, mortality was substantially reduced (1.04, 1.00-1.08) after adjusting for standard care, socio-demographics, tumor characteristics, prognostic factors and chemotherapy. Therefore, ADT was not associated with significantly increased survival benefit for older men with locoregional CaP. Further studies may be needed to explore whether ADT is associated with other health benefits and the cost-effectiveness of these benefits.