PURPOSE: Preoperatvie radiotherapy has many theoretical advantages in contrast to postoperative one such as preventing dissemination of cancer cells during surgery and increasing resectability rate by down-staging, thus more feasibility of preserving anus and improving survival. But there are several adverse effects, too. Distant metastasis can be detected after preoperative radiotherapy. Postoperative complication rate is high. Pathologic stage is changed after preoperative radiationtherapy so that there is difficulty in prediction of prognosis. We reviewed distant metastasis after preoperative radiotherapy and evaluated detection rate of metastasis with computed tomography in rectal cancer. METHODS: Fifty patients with histologically proven rectal cancer and locally advanced lesions, as determined by physical examination and with no distant metastasis on preoperative computed tomography, entered the trial from 1990 to 1999. Surgery followed 2 to 6 weeks after completion of hyperthermia-chemoradiotherapy (HTCRT). Preoperative stages were determined with computed tomography. Postoperatve stage were determined by pathologic study. RESULTS: Thirty cases were male. Twenty cases were female. Distance from anal verge to tumor were under 7 cm of 36 cases, over of 14 cases. The median tumor size was 3.3 cm in diameter. The conservation rate of anal sphincter function were 48.0%. In preoperative staging with computed tomography, the number of stage I, II, and III were 4, 11 and 35 cases. none were stage IV. The overall resectability rate was 90.0% (45 of 50 patients). In postoperative staging with pathologic study, the number of stage 0, I, II, and III were 4, 5, 19, and 13 cases. stage IV were 9 cases. Anastomotic leakage were noticed in 2 cases. In stage IV cases, liver metastases were noticed in all cases. CONCLUSIONS: The preoperative radiotherapy was applied to the 50 patients with rectal cancer. The liver metastases which were detected after preoperative radiotherapy were 9 cases. The false negative value of computed tomography for liver metastasis in rectal cancer was 18.0%. We need more sensitive study for detecting liver metastasis of rectal cancer, especially in scheduled preoperative radiotherapy.