Introduction: The objective of this study was to evaluate the therapeutic significance of a longer duration of neoadjuvant hormonal therapy (NHT) followed by radical prostatectomy (RP) in Japanese men with high-risk prostate cancer. Materials and Methods: This study included a total of 42 patients with high-risk prostate cancer who were treated with NHT for ≧8 months prior to RP. In this series high-risk prostate cancer was defined as clinical stage T2c or T3, pretreatment serum prostate-specific antigen (PSA) >20 ng/ml and/or a biopsy Gleason score of 8–10. Biochemical recurrence was defined as a serum PSA level of ≧0.2 ng/ml. The data of these patients were retrospectively reviewed to clarify the relationships between treatment outcomes and various clinicopathological parameters. Results: The clinical stage was T2c in 13 patients and T3 in 29, the median value of pretreatment serum PSA was 43.3 ng/ml (range 9.7–322.2), and the biopsy Gleason score was 6 in 3 patients, 7 in 16 and ≧8 in 23. Following NHT (median 12 months, range 8–27), the median value of serum PSA decreased to 0.05 ng/ml (<0.01–18.3 ng/ml), and 15 patients (35.7%) were pathologically downstaged. During the median follow-up of 38 months (range 8–58), 11 patients (26.2%) developed biochemical recurrence, and the multivariate analysis identified pretreatment serum PSA, biopsy Gleason score and percentage of positive biopsy core as independent predictors of biochemical recurrence. The 3-year biochemical recurrence-free survival rate of the 42 patients was 68.3%, which was not significantly different from that of 34 patients who underwent RP for high-risk prostate cancer without NHT during the same period. Conclusion: A longer duration of NHT followed by RP for patients with high-risk prostate cancer resulted in a comparatively favorable outcome. However, despite the nonrandomized retrospective analysis, the present findings suggest no significant impact of long-term NHT on biochemical recurrence. Longer follow-up is needed to determine whether this therapeutic strategy is beneficial for high-risk prostate cancer patients.