PURPOSE: To determine the efficacy and tolerability of combining oxaliplatin with capecitabine in the treatment of advanced nonpretreated and pretreated colorectal cancer. PATIENTS AND METHODS: Forty-three nonpretreated patients and 26 patients who had experienced one fluoropyrimidine-containing regimen for advanced colorectal cancer were treated with oxaliplatin 130 mg/m(2) on day 1 and capecitabine 1,250 mg/m(2) bid on days 1 to 14 every 3 weeks. Patients with good performance status (World Health Organization grade 0 to 1) were accrued onto two nonrandomized parallel arms of a phase II study. RESULTS: The objective response rate was 49% (95% confidence interval [CI], 33% to 65%) for nonpretreated and 15% (95% CI, 4% to 35%) for pretreated patients. The main toxicity of this combination was diarrhea, which occurred at grade 3 or 4 in 35% of the nonpretreated and 50% of the pretreated patients. Grade 3 or 4 sensory neuropathy, including laryngopharyngeal dysesthesia, occurred in 16% of patients on both cohorts. Capecitabine dose reductions were necessary in 26% of the nonpretreated and 45% of the pretreated patients in the second treatment cycle. The median overall survival was 17.1 months and 11.5 months, respectively. CONCLUSION: Combining capecitabine and oxaliplatin yields promising activity in advanced colorectal cancer. The main toxicity is diarrhea, which is manageable with appropriate dose reductions. On the basis of our toxicity experience, we recommend use of capecitabine in combination with oxaliplatin 130 mg/m(2) at an initial dose of 1,250 mg/m(2) bid in nonpretreated patients and at a dose of 1,000 mg/m(2) bid in pretreated patients.