PURPOSE: To evaluate antitumor response, time to progression, and toxicities of oxaliplatin, 5- fluorouracil (5-FU), and leucovorin (LV) continuous infusion in patients with metastatic colorectal cancer who progressed during or after treatment with a 5-FU-containing regimen. MATERIALS AND METHODS: Forty-eight patients with metastatic colorectal cancer, who progressed while receiving or after discontinuing palliative chemotherapy with 5- FU-based regimen, were enrolled in this study. Treatment consisted of oxaliplatin (85 mg/m2 on day 1) as a 2-hour infusion followed by bolus 5-FU (400 mg/m2 on day 1), and 5-FU 48-hour infusion 2.4~3 g/m2 concurrently with LV 48-hour infusion 150 mg/m2, without mixing. Cycles were repeated at 2-week intervals. The dose of 5-FU was modified, depending on the hematologic toxicity profile. RESULTS: The objective response rate was 28% for 43 assessable patients (95% confidence interval, 14% to 42%), including one complete remission (2%). Seventeen additional patients (39%) had stable disease, and fourteen (33%) progressed. The median time to progression was 5.9 months and the median overall survival was 13.2 months from the start of the chemotherapy. From the 297 cycles analyzed, hematologic toxicities per course were: leukopenia; grade I 26.6%, grade II 3.4%, and grade III 0.3%, thrombocytopenia; grade I 10.8%, grade II 3.0%, grade III 1.0%, and grade IV 0.3%. The most frequent nonhematologic adverse reactions were nausea/vomiting and peripheral neuropathy, which were rated as WHO grade II in 13 patients (49%) and 11 patients (22%), respectively. CONCLUSION: This phase II study of oxaliplatin, 5-FU, and LV continuous infusion showed enhanced antitumor activity in patients with 5-FU-pretreated metastatic colorectal cancer. Overall toxicity was acceptable; neurotoxicity and bone marrow suppression constituted the dose-limiting side effects.