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. Minty two patients of carcinoma of the rectum after curative surgery received post operative radiotherapy $5,000rad/5~6weeks$ to whole pelvis at the Department of Therapeutic Radiology, Seoul National University Hospital between March 1979 and December 1982. Fifty three percent of patients show modified Astler-Coiler 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 analysed. Incidence of small bewel obstruction, requiring surgery, is $8\%$, occurring between 5th month to 12 th 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.