Androgen deprivation therapy is often used as salvage treatment in men with rising prostate specific antigen after initial radical prostatectomy or radiotherapy for clinically localized prostate cancer. Given the lack of evidence from general practice, we examined the association of salvage androgen deprivation therapy with mortality in an observational cohort study. From 3 managed care organizations we assembled a retrospective cohort of all 5,804 men with newly diagnosed localized prostate cancer from 1995 to 2009 who had a prostate specific antigen increase (biochemical recurrence) after primary radical prostatectomy or radiotherapy. The main outcomes were all-cause and prostate cancer specific mortality. We used Cox proportional hazards models to estimate mortality with salvage androgen deprivation therapy as a time dependent predictor. Overall salvage androgen deprivation therapy was not associated with all-cause or prostate cancer specific mortality in the prostatectomy cohort (HR 0.97, 95% CI 0.70-1.35 or HR 1.18, 95% CI 0.68-2.07) or in the radiotherapy cohort (HR 0.84, 95% CI 0.70-1.01 or HR 1.06, 95% CI 0.80-1.40, respectively). Among men with prostate specific antigen doubling time less than 9 months after the prostate specific antigen rise, salvage androgen deprivation therapy was statistically significantly associated with a decreased risk of all-cause and prostate cancer specific mortality in the prostatectomy cohort (HR 0.35, 95% CI 0.20-0.63 and HR 0.43, 95% CI 0.21-0.91) and in the radiotherapy cohort (HR 0.62, 95% CI 0.48-0.80 and HR 0.65, 95% CI 0.47-0.90, respectively). We found no association of salvage androgen deprivation therapy with all-cause or cause specific mortality in most men with biochemical recurrence after primary radical prostatectomy or radiotherapy for clinically localized prostate cancer. Men with quickly progressed disease may derive a clinical benefit from salvage androgen deprivation therapy.