Prostatic involvement with transitional cell carcinoma of the bladder is common. Surveillance for prostatic invasion consists primarily of cystoscopic examination of the urethra. Unfortunately, transitional cell carcinoma may involve other regions of the prostate that are inaccessible by cystoscopy. A total of 58 men with transitional cell carcinoma of the bladder underwent transrectal ultrasound before cystoprostatectomy or, in some cases, ultrasound-guided prostate biopsies and subsequent cystoprostatectomy. Prostatic involvement was found in 20 patients (34.5%). Of those patients 10 (50%) demonstrated prostatic urethra invasion, 7 (35%) stromal invasion, 4 (20%) ejaculatory duct and seminal vesicle invasion, and 3 (15%) involvement of the periprostatic tissues. Invasion of the prostatic urethra was not detected by transrectal ultrasound but 5 of the 7 stromal lesions exhibited hypoechogenicity. All cancer-laden ejaculatory ducts were hypoechoic on ultrasound examination. All cases of periprostatic involvement were also detectable by corresponding areas of hypoechogenicity. Transrectal ultrasound may enhance the surveillance of men with transitional cell carcinoma.