The treatment of stage C (T3) adenocarcinoma of the prostate using external beam radiation therapy (RT) reportedly achieves clinical local control of approximately 70-80%. A dose relationship to local control has been demonstrated in prostate cancer, although a dose-related increase in complications has also been observed. To determine the maximum dose deliverable to the prostate gland while maintaining an acceptable complication rate, a prospective dose-escalation trial using a conformational planning and dose-delivery technique was initiated for patients with stage C (T3) disease. Initial results reported here are encouraging.