The purpose of this paper to identify the optimal therapy after radical prostatectomy (RP) for patients with adenocarcinoma of the prostate invading the seminal vesicles (pT3bN0M0 or SVI). A PubMed search using the keywords 'prostate', 'seminal vesicle', 'prostatectomy', 'radiotherapy', 'androgen blockade' was performed to identify literature regarding rates of disease failure in patients with SVI who are observed or treated with androgen blockade (AB), radiotherapy (RT) or RT þAB after RP. The outcome of 68 patients treated at Duke University with post-operative AB, RT or RT þAB for pT3bN0M0 is also presented. More than 70% of patients with SVI develop disease recurrence after surgery. For many, recurrence occurs within 2 y after RP. These patients have poor control rates with postoperative RT alone. While experience with AB and RT þAB is limited, control rates are generally superior to RT alone. At Duke University, after a median followup of nearly 4 y, patients treated with RT þAB or AB alone for pT3bN0M0 achieved better 5-y progression-free survival (PFS) compared with those who received RT alone (78 and 68 vs 30%, P ¼ 0.03 and 0.046, respectively). There was no PFS difference between those who received AB alone or RT þAB (68 vs 78%, P ¼ 0.5). Seminal vesicle invasion confers a poor prognosis after RP. SVI is a consistent predictor of poor outcome after RT. The limited data available examining AB and RT þAB in pT3bN0M0 disease, including data from Duke University, are encouraging. Nonetheless, postoperative AB, RT and RT þAB for pT3bN0M0 disease require prospective evaluation, as RP alone is rarely curative.