The purpose of this study was to identify the early predictor of survival for prostate cancer patients with bone metastasis. We reviewed 87 prostate cancer patients with bone metastasis who had received primary androgen deprivation therapy (PADT) at our institution. The medical records of the patients were examined with respect to laboratory data, pathological results, PSA response to PADT and clinical outcome. The overall survival (OS) rates were analyzed with reference to the nadir PSA level and time to PSA nadir (TTN) following PADT by Kaplan-Meier method. In all, 59 patients (67%) had progression to castration-resistant prostate cancer. Nadir PSA <0.2 ng ml(-1) (lower PSA nadir) during PADT were observed in 47 patients (54%). Multivariate analysis revealed that the extent of disease on bone scan (P=0.04), lower PSA nadir following PADT (P=0.003), albumin (P=0.04) and lactate dehydrogenase (P=0.01) were independent prognostic factors for survival. OS rates in the patients with lower PSA nadir were significantly higher. Longer TTN (>9 months) identified patients with prolonged OS in both lower and higher PSA nadir groups. PSA nadir <0.2 ng ml(-1) and prolonged TTN (>9 months) following PADT might be the most important early predictors for longer survival in prostate cancer patients with bone metastasis.