Administration of Bacillus Calmette-Guerin (BCG) has been shown to cause granulomatous prostatitis, a rare inflammatory process that can be mistaken for prostate cancer. We present a case of a 78-year-old man on active surveillance for prostate cancer with a subsequent diagnosis of high-grade urothelial carcinoma. After intravesical BCG therapy, he developed chronic granulomatous prostatitis. We present serial magnetic resonance imaging and biopsy data demonstrating the time interval between BCG administration and the manifestation of chronic granulomatous prostatitis. © 2014 by Lippincott Williams & Wilkins.