Surgery remains the mainstay in the management of carcinoma of the rectum. However, Local recurrence and systemic metastasis remain the challenge. It appears that post operative radiotherapy has a very definite role in the reduction of local recurrence. Ninety two patients of carcinoma of the rectum after curative surgery received post operative radiotherapy 5,000 rad/5~6 weeks to whole pelvis at the Department of Therapeutic Radiology, Seoul National University Hospital between March 1979 and December 1982. Fifty three percent of patients pf patients show modified Astler-oller stage C2. Actuarial disease free survival rate of rectal cancer was: stage B1,2 75%, stage C1 81% stage C2 39%, and stage C3 20%. Twelve percent shows local recurrence and distant metastasis occurred in 28%. Prognostic significance of nodal metastasis is also analyzed. Incidence of small bowel obstruction, requiring surgery, is 8%, occurring between 5th month to 12th month after operation. It is suggested that post operative radiotherapy of the rectal cancer following curative surgery has a significant role in the reduction of local recurrence.