252 Background: Post radical prostatectomy patients (RP) with extra prostatic extension or high Gleason grade are considered to have a high risk of treatment failure. Actual role of LH-RH agonists after RP in patients with high risk of recurrence remains unclear, except for the patients with positive lymph nodes. No randomized prospective study has been published with LH-RH agonists in the PSA era. Recent SWOG 9921 study shows a favorable disease-free and 5-year overall survival of 96% for high-risk patients treated with 24 months of ADT after surgery. However, this study does not define the optimal protocol of adjuvant ADT, and does not demonstrate the superiority of immediate vs delayed treatment. The Objective of the AFU-GETUG 20 study is to evaluate the benefit of leuprorelin acetate for 24 months after RP in patients with high risk of recurrence. Methods: Academic Phase III randomised, open-label, multicenter trial starting in late 2011. Inclusion criteria : R0, N0-Nx M0 patients after RP in the 3 months preceding inclusion and with postoperative Gleason score > 7, or ≥ 7 with the presence of 5 grade Gleason patterns or, or pT3b tumor, and with postoperative PSA < 0.1 ng/mL. Exclusion criteria : previous/current therapy for PCa. Primary endpoint is the evaluation of metastatic progression free survival. Secondary endpoints include overall survival, disease-specific survival, PSA evolution, evaluation of testosterone level, and quality of life. Results: A total of 700 patients (350 in each arm) and 250 events are required to have 80% ability to detect a difference with a bilateral Logrank test with α= 0.05 and β= 0.20. Decision rules will be determined by the O’ Brien-Fleming sequential boundaries at the time of the analysis. Interim analysis is planned at the 125th event (50% of events) for 6.5 years after the start of the trial. Final analysis is planned for 12 years after the inclusion of the first patient. Conclusions: The AFU-GETUG 20 study is a pioneering French multicenter trial aiming to evaluate the actual role and place of ADT after RP for patients with high-risk prostate cancer.