We analyzed the ultrasound findings and the information obtained from serial whole-mount cross-section histologic examination of the prostates from 6 patients with bacillus Calmette-Guérin (BCG)-induced granulomatous prostatitis. Similarities to prostate cancer included a hypoechoic pattern on ultrasound, multifocality, and a propensity for a peripheral zone location. BCG-induced granulomatous prostatitis cannot be distinguished from cancer by ultrasonography. We suggest performing an ultrasound examination prior to starting BCG immunotherapy as a baseline for future reference to aid in the clinical diagnosis of BCG-induced granulomatous prostatitis.