Objective: Locally advanced prostate carcinoma frequently causes lower urinary tract symptoms and is a clinical challenge when radiation and/or hormone therapy fail. We investigated whether cystoprostatectomy with urinary diversion benefits patients with locally advanced prostate carcinoma in terms of quality of life and prognostic outcome. Patients and Methods: Between 1989 and 2001, we performed 15 cystoprostatectomies for stage C-D1 prostate carcinoma with bladder neck involvement. Of these patients, 5 underwent ileal conduit, 8 rectal bladder, 1 Koch pouch, and 1 ureterocutaneostomy. All the patients received neoadjuvant and/or adjuvant hormonal therapy. In the same period, 28 patients underwent retropubic prostatectomies and 15 patients received hormone therapy alone for stage C-Dl disease. These patients were included as references. Results: Lower urinary tract symptoms caused by bladder involvement were controlled well until the end of follow-up for all the patients in the cystoprostatectomy group. There was no statistically significant difference in QOL score assessed with the EORTC QLQ-C30 questionnaire between the prostatectomy group and the cystoprostatectomy group, while that in the hormone therapy group was lower than those in the surgery groups. There was no statistically significant difference in 5-year PSA-relapse-free survival among cystoprostatectomy, prostatectomy, and hormone therapy groups. Patients in the hormone therapy group died earlier than those in the prostatectomy group (p = 0.02), while those in the cystoprostatectomy group did not. Conclusion: These results suggest that total cystoprostatectomy with urinary diversion is a valid option, in terms of disease control and QOL, for prostate cancer patients whose tumor is infiltrating into the bladder.