OBJECTIVE: To assess the treatment recommendations from a nationally representative sample of radiation oncologists and urologists on adjuvant radiotherapy for patients with pathologically advanced prostate cancer after radical prostatectomy. METHODS: From a random sample of 1422 physicians (n = 711 radiation oncologists; n = 711 urologists) in the American Medical Association Masterfile, a mail survey queried treatment recommendations for adjuvant radiotherapy that varied by the following pathologic features: extraprostatic extension (pT3a) vs seminal vesicle invasion (pT3b), Gleason 7 vs Gleason 8-10, and margin negative (MN) vs margin positive (MP). Pearson chi-square and multivariable logistic regression were used to test for differences in treatment recommendations by physician specialty. RESULTS: Response rates for radiation oncologists and urologists were similar (44% vs 46%; P = .42). Radiation oncologists were more likely to recommend adjuvant radiotherapy than urologists for all the varying pathologic scenarios from pT3a, Gleason 7, and MN (42.5% vs 9.7%; adjusted odds ratio [OR]: 7.82, P <.001) to pT3b, Gleason 8-10, and MP disease (94.5% vs 89.1%, adjusted OR: 2.46, P <.001). Compared with radiation oncologists, urologists were more likely to recommend salvage radiotherapy pT3a, Gleason 7, and MN (90.3% vs 57.7%; adjusted OR: 7.72, P <.001) to pT3b, Gleason 8-10, and MP disease (10.9% vs 5.5%; adjusted OR: 2.22, P <.001). CONCLUSION: In this national survey, radiation oncologists and urologists have markedly different treatment recommendations for adjuvant and salvage radiotherapy. Patients with adverse pathologic features after radical prostatectomy should consult with both a urologist and radiation oncologist to hear a diversity of opinions to make the most informed decision possible.