Purpose: Despite apparently complete resection of cancer of the rectum, local recurrence rate was high. Radiation therapy has been used either alone or in combination with chemotherapy as an adjunct to surgery to reduce the risk of recurrence. This study was designed to evaluate the prognostic factors, survival rate and local recurrence rate of the rectal cancer who had received postoperative radiation therapy by retrospective analysis. Method: From 1982 to 1990, 63 patients with cancer of the rectum surgically staged as B2 or C disease received postoperative adjuvant radiation therapy after curative resection of tumor for cure. Postoperative radiation therapy was given to the whole pelvis(mean dose: 5040 cGy in 5-6weets) and perineum was included in irradiated field in case of abdominoperineal resection. Results: Three-year actuarial survival rate was 73.2$ \% $ overall, 87.7$ \% $ in stage B2+3 and 62.9$ \% $ in stage C2+3. Three-year disease-free survival rate was 69.5$ \% $ overall, 87.7$ \% $ in stage B2+3 and 56.8$ \% $ in stage C2+3, Three-year disease-free survival rate in anterior resection was 77.8$ \% $ and 44.4$ \% $ in abdominoperineal resection. The local recurrence rate was 15.9$ \% $ and distant failure rate was 20.6$ \% $. Severe late complication was small bowel obstruction in 6 patients and surgery was required in 4 patients(6.3$ \% $). The prognostic factors were stage(p=0.0221) and method of surgery(p= 0.0414) (anterior resection vs abdominoperineal resection). Conclusion: This study provides evidence supporting the use of postoperative radiation therapy for reducing the local recurrence rate in patients who have had curative resection of rectal cancer with involvement of perirectal fat or regional nodes or both(stage B2 and C).