OBJECTIVES: I. Determine the maximum tolerated dose of capecitabine when combined with oxaliplatin in patients with chemotherapy naive or thymidylate synthase inhibitor pretreated unresectable, advanced or metastatic colorectal cancer. II. Determine the safety profile, toxicity, and efficacy of this regimen in these patients. III. Determine the complete and partial remission rates, time to treatment failure, and overall survival of patients treated with this regimen.