From January 1983 until June 1987, 51 patients with locally advanced prostatic carcinoma (47 Stage C, 4 bulky B2) were treated at Mayo Clinic (33 patients) and at William Beaumont Hospital (18 patients) with (a) 5 Gy delivered pre-operatively in one fraction, (b) pelvic lymphadenectomy and (c) interstitial implantation of the prostate with Ir 192 seeds via a perineal template (the Martinez Universal Perineal Interstitial Template) to deliver 35 Gy, and (d) 30.6 Gy external beam therapy in 17 fractions to prostate only fields. Initial clinical response has been excellent. Local control, with a median follow-up of 45 months, has been 100% by clinical exam and 84.5% pathologically in the subset biopsied. Disease-free actuarial survival at 5 years is 89%. Major toxicity has been limited to the rectum, but a modification of the brachytherapy technique has reduced this sharply. We conclude that bulky Stage C prostatic carcinoma can be successfully treated by this aggressive combination of modalities with acceptable toxicity.