Background: Three randomized clinical trials have established brachytherapy (BT) boost in combination with external beam radiation therapy (EBRT) and androgen deprivation therapy (ADT) as superior to definitive EBRT and ADT alone in terms of biochemical control (but not overall survival) at the expense of increased toxicity in men with high-risk (HR) prostate cancer (PCa). The current view regarding these two treatment algorithms among North American genitourinary (GU) experts is not known. Methods: A survey was distributed to 88 practicing North American GU physicians serving on decision-making committees of cooperative group research organizations. Questions pertained to opinions regarding BT as monotherapy for low-risk (LR) PCa and BT boost for HR PCa. Responders were asked to self-identify as BT experts vs non-experts. Treatment recommendations were correlated with practice patterns using Fisher’s exact test. Results: Forty-two radiation oncologists completed the survey, of whom 23 (55%) recommend EBRT and ADT alone and 19 (45%) recommend addition of BT boost. Twenty-five participants (60%) identified themselves as BT experts. Nearly 90% of those recommending BT boost were BT experts versus approximately 10% of non-BT experts (p < 0.001). Responders who recommended BT monotherapy as first-choice treatment for LR PCa were more likely to recommend BT boost for HR PCa (p < 0.0001). Conclusions: There is a dramatic polarization in opinions regarding incorporation of BT boost into EBRT+ADT therapy for patients with HR PCa among North American GU radiation oncology experts, who serve on decision-making committees and influence the national treatment guidelines and future clinical trials. Those who identify themselves as BT experts are significantly more likely to recommend BT boost, which may serve as a self-fulfilling prophecy regarding the role of BT in North American clinical practice. These findings are likely to influence the national guidelines and implementation of BT boost in current and future North American PCa clinical studies.