We herein report two cases of locally recurrent rectal cancer that were successfully treated by surgical resection of shrunken tumor by pre-operative CRT. Although one case had a relapse in 7 months after the operation, the prognostic difference between two cases was discussed. CASE 1: A 54-year-old male had a pre-sacral mass (54 mm) six months after an anterior resection for advanced rectal cancer. We planned a surgical resection after CRT (radiation 50 Gy, CPT-11, UFT and LV). The tumor had a good response (33 mm) allowing a dissection area between sacral bone and posterior margin. Low anterior resections with sacral bone resection (below S3) were done to prevent S1 nerve roots injury and spinal fluid leakage. Macroscopically, a surgical margin was well secured. The patient is alive for 84 months after the surgery without an evidence of recurrence. CASE 2: A 66-year-old man had an anal bleeding. He underwent Hartmann's maneuver for advanced rectal cancer. MRI revealed a recurrent tumor (66 mm) occupying up to the 1st sacral bone. CRT was carried out. After a tumor response was (35 mm) obtained, and total pelvic exenteration with sacral bone resection below S3 was carried out, achieving R0 operation. However, He had relapsed at 7 months after the operation.