OBJECTIVE : Adjuvant radiotherapy (ART) for biochemical relapse (BR) after radical prostatectomy (RP) showed increased disease-free survival (DFS) in three previous randomized trials. Retrospective phase II trials evaluated if early salvage RT (ESRT) is equivalent to ART. Our study aims to compare ART and ESRT to salvage RT. METHODS : We compared RP plus ART and ESRT versus SRT. Indication for RT was made by PSA determination after RP: ART when PSA ≤ 0.2 ng/ml, ESRT when PSA ≤ 0.3 after PSA rise from 0.0 to SRT PSA ≥ 0.3. The cause of death of each patients was analyzed, DFS, cause-specific survival (CSS) overall survival (OS) and metastasis-free survival (MFS) in relation to RT intention. RESULTS : Between 1993 and 2008, 204 patients with a median age of 65 years (44-75) were treated. The median follow-up was 160 months (28.1-273.3). At diagnosis, 89.7% had localized clinical stages and 90.2% had Gleason (G) ≤ 7. The median PSA was 10 (range 4-101). The postoperative G was ≥ 7 in 66.2%; 56.4% had ≥ 2 positive margins; 29.4% received ART, 20% ESRT and 59.3% SRT. The DFS for ART, ESRT and SRT was 74, 56 and 39% with significant differences between the three groups (p < 0.001). ART + ESRT were combined versus SRT; for the DFS, the significant differences (p < 0.001) remained 67% versus 39%. Positive margins, pT3 and pre-RT PSA were significant factors on multivariate analysis. The CSS in the ART + ESRT group was 92 vs. 78% in the SRT group (p < 0.05). OS was 69% in ART + ESRT vs. 57% in SRT (p < 0.05). MFS was 82.7% in ART + ESRT vs. 67.4% in SRT. CONCLUSIONS : In this study the ART + ESRT presented benefits versus SRT in DFS, CSS, OS and MFS.