The authors investigated local recurrence of rectal cancer in patients' groups preoperatively irradiated (40-50 Gy) or treated by surgery alone. In advanced disease both treatment groups were administered postoperative chemotherapy, too. Local recurrence was observed in 30.2% in patients treated by surgery alone, while it dropped to 11.65% in the patients' group subjected to radiation therapy prior to surgery (p < 0.05). Impairment of degree of differentiation resulted in an enhanced number of recurrences in both groups, even if they appeared later in irradiated patients.