The pertherapeutic intolerance and morbidity are analyzed in a group of 597 patients with localized prostatic carcinoma treated by definitive radiotherapy between 1975 and 1982. Minimum follow-up is 2 years, median is 46 months. The results are compared to following parameters: associated diseases, associated surgical treatments, doses and irradiated target volumes. Pertherapeutic intolerance manifestations were found in 73% of patients and lead to complications. Urinary incontinence and chronic cystitis were more frequent after transurethral resection or prostatic surgery. Proctitis was the most disabling and can be reduced by a better estimation of prostatic target volume and by split course irradiation. Chronic diarrhea was more frequent when using large target volume. Leg edema was closely associated with pelvic lymphadenectomy. The control of pertherapeutic manifestations and the prevention of complications should improve survival in patients treated by external radiotherapy.