Purpose: The efficacy of a multimodality protocol using neoadjuvant and concomitant hormonal therapy, brachytherapy, and three-dimensional conformal external beam radiotherapy (RT) in high-risk prostate cancer was evaluated using biochemical outcomes and posttreatment biopsy results. Methods and Materials: Between February 1994 and November 1999, 132 high-risk patients were treated with combined hormonal therapy (9 months), permanent radioactive seed brachytherapy, and external beam RT, with follow-up ranging from 36 to 88 months (median, 50 months). The eligibility criteria were any of the following: Gleason score 8-10, initial prostate-specific antigen (PSA) level >20 ng/mL, clinical Stage T2c-T3, or positive seminal vesicle biopsy, or two or more of the following: Gleason score 7, PSA level >10-20 ng/mL, or Stage T2b. Twenty percent of patients had a positive seminal vesicle biopsy before therapy. Negative laparoscopic pelvic lymph node dissections were performed in 44% of patients. Results: The actuarial overall freedom from PSA failure rate was 86% at 5 years. The freedom from PSA failure rate at 5 years was 97% for those with a Gleason score of less than or equal to6 (35 of 36), 85% for a Gleason score of 7 (50 of 59), and 76% for a Gleason score of 8-10 (28 of 37; p = 0.03). A trend was noted toward worse outcomes in seminal vesicle biopsy-positive patients, with a 5-year freedom from PSA failure rate of 74 % vs. 89 % for all other patients (p = 0.06). Posttreatment prostate biopsies were performed in 47 patients and were negative in 96% at the first biopsy and 100% at the last biopsy. Conclusion: Trimodality therapy with androgen suppression, brachytherapy, and external beam RT for high-risk prostate cancer results in excellent biochemical and pathologically confirmed local control. (C) 2004 Elsevier Inc.