The evaluation of clinical stage C prostatic cancer has been enhanced by advances in staging modalities over the past 15 years. Better staging of the local lesion is possible with transrectal ultrasound-guided multiple biopsies of the prostate and its vicinity. Biopsies of suspect pelvic lymph nodes guided by CT (or lymphangiography) may obviate pelvic lymphadenectomy, particularly in patients with high-grade stage C lesions. Advances in the understanding of serum markers have supplemented other staging information. No single therapeutic modality is appropriate for all cases of clinical stage C cancer. In C1 lesions, radical prostatectomy with adjunctive radiation or hormonal therapy seems to produce the best 5- and 10-year survival rates. External-beam radiation alone, or in combination with interstitial radiation, may have equivalent success. In clinical stage C2 disease, external-beam radiotherapy seems at present to be the best therapeutic modality. Interstitial radiation as a sole method of management in stage C disease carries a high local recurrence rate and a significant risk of metastatic progression. Transurethral prostatectomy and hormonal treatment continue to have a place in the management of selected poor-risk patients. The current results with surgery or radiation therapy alone are less than ideal. It is recommended that aggressive combination treatment be compared with monotherapy in randomized clinical trials monitored jointly by radiation and urologic oncologists.