PURPOSE: The purpose of this study was to evaluate the clinicopathological significance of responders with metastatic colorectal cancer treated with oxaliplatin chemotherapy. METHODS: A total of 52 patients with unresectable metastatic colorectal cancer were enrolled for treatment between March 2000 and August 2005. Patients received first line chemotherapy consisted of oxaliplatin 85 mg/m2 or 130 mg/m2 as a 2-hour infusion on day 1, concurrently with leucovorin (LV) 20 mg/m2 as a bolus infusion on day 1~5, followed by continuous infusion of 5-fluorouracil (5-FU) 425 mg/m2 on day 1~5. This treatment was repeated in 2 or 3 week intervals. All responses were assessed after 4 cycles of therapy by independent radiologic experts and categorized into two groups: responder (major reduction of tumor) and non-responder group (no change or progression of the tumor. RESULTS: The response rate was 51.9 percent (27/52 patients). There were no significant differences in clinicopathologic parameters between two groups. The decrease of CEA value after chemotherapy was significantly more frequent in the responder group than in the non-responder group. CONCLUSIONS: We could not find any clinical differences between the two groups, but these results suggest that oxaliplatin chemotherapy has a beneficial effect on tumor shrinkage and serum CEA value can be an indicator for tumor response of oxaliplatin in advanced colorectal cancer.