OBJECTIVE To present the long-term outcome and morbidity of high-dose-rate brachytherapy (HDR-BT) combined with external beam radiotherapy (EBRT) for localized prostate cancer. METHODS Between September 1991 and December 1998, 209 consecutive patients with no prior androgen suppression were treated with HDR-BT plus EBRT. The median follow-up was 7.25 years (range, 5-12 years). The patients were stratified into three risk groups: low (Stage T2a or less, Gleason score </=6, and prostate-specific antigen [PSA] level </=10 ng/mL), intermediate (Stage T2b,c, Gleason score 7, and PSA level 10-20 ng/mL), and high (Stage T3, Gleason score 8-10, and PSA level >20). Four definitions of PSA progression were compared with the general clinical failure outcome: the American Society for Therapeutic Radiology and Oncology (ASTRO) definition, nadir plus 2.0 ng/mL, two consecutive rises >/=0.5 ng/mL, and PSA level >0.2 ng/mL. Morbidity was scored using Radiation Therapy Oncology Group criteria. RESULTS The general clinical control rate was 90% (188 of 209), and the general clinical failure rate was 10% (21 of 209). The overall survival rate was 79%, and the cause-specific survival rate was 97%. The PSA progression-free survival (ASTRO definition) rate was 90%, 87%, and 69% for the low-, intermediate-, and high-risk groups, respectively. The nadir plus 2 ng/mL and two rises >/=0.5 definitions correlated better with the actual clinical outcome than did the ASTRO and PSA >0.2 ng/mL definitions. The rate of Grade 3 and 4 late urinary morbidity was 6.7% and 1%, respectively, mostly occurring in patients who had undergone post-RT transurethral prostate resection. No late Grade 3 or 4 rectal morbidity developed. The sexual potency preservation rate was 67%. CONCLUSIONS Our 10-year results have demonstrated HDR-BT plus EBRT is a proven treatment for all stages of localized prostate cancer. The morbidity was low, but post-RT transurethral resection should be avoided.