The protracted natural history of prostate cancer and the absence of a documented effective seconde line curative therapy, once primary treatment has failed, has led in the presence of biochemical failure after radical prostatectomy to a dual attitude: early treatment versus observation with delayed therapy. The objective of this review is to define the subsets of patients who might benefit from either of these attitudes. Depending on the risk of progression, three subgroups of patients may be individualized: a high-risk group (PN1, pT3 B, Gleason score equal or superior to 8), a moderate-risk group (pT3 A, NO with positive margins, and a Gleason score equal or less than 7), and a low-risk group (pT2 NO or pT3 A NO without positive margins and Gleason score equal or lower than 7). As of today, observation seems to be the appropriate option in men with a low or moderate risk of progression, whereas in the high-risk group, early therapy is a reasonable option. New treatment options with intermittent hormonal therapy or with combined adjuvant hormonoradiotherapy show a promising efficacy that may lead to reconsider this attitude.