January 1985 to June 1991, seventy-five patients affected with surgically treated rectal cancer received adjuvant postoperative irradiation at the Radiation Therapy Department of the Ospedale S. Maria Nuova, Reggio Emilia, Italy. Forty-seven patients had Astler-Coller B2-B3 lesions and 28 had stage C2-C3 disease. The patients underwent postoperative irradiation (range: 44-60 Gy, median: 48.5 Gy) with a 60 Co unit, most of them with conventional fractionation; no patient received adjuvant chemotherapy. A local boost was used in 19 cases (5.4-14 Gy); actuarial 5-year overall and disease-free survival rates were 55.2 +/- 10.5% and 53.4 +/- 10%, respectively; actuarial 5-year local control was 78.7 +/- 10.5%. In 11 cases (14.5%) chronic sequelae were observed; 6 cases required surgical intervention. In 42% of cases the disease relapsed, locally in 12 patients (16%). In conclusion, our results are in agreement with literature data; adequate and innovative techniques are required to decrease treatment-related toxicity.