Background: This study was designed to suggest the possibility of hormone-related derangement in salvage radiotherapy (SRT) after radical prostatectomy in terms of prostate-specific antigen (PSA) control. Materials and Methods: Among 160 consecutive prostate cancer patients who received radical prostatectomy, 34 with SRT between 2004 and 2012 were retrospectively reviewed. The numbers of patients with pathologic T3-T4 stage, Gleason score 8-10, and positive resection margin were 11 (32.4%), 10 (29.4%), and 17 (50.0%), respectively. Median SRT dose was 64.8 Gy (range, 52.9-70.0 Gy) with 1.8-2.3 Gy fractionations. Biochemical failure-free survival after SRT was counted and the median follow-up period was 32.5 months (range, 10-118 months). Results: After SRT, the median time for PSA to decrease to less than 0.2 ng/mL was four months (range, 0-25 months). The three-year survival rate was 60.3%. On univariate analysis, preferential hormone therapy (PHT) (p=0.022), higher PSA at SRT (p=0.005), and higher PSA after surgery (p=0.003) were related to a shorter biochemical survival period. On multivariate analysis, lower PSA at SRT (p=0.016), higher radiation dose (p=0.007), and non-PHT (p=0.046) suggested a consistent PSA control. Conclusion: According to these results, low PSA values by hormonal intervention need to be reconsidered with a different way to look at the relationship between the PSA and hormone therapy. SRT should be considered for postoperative salvage treatment regardless of the hormone-related PSA values.