AIM: This study was designed to determine the efficacy and tolerability of capecitabine, oxaliplatin and bevacizumab in combination with cetuximab as first-line therapy for advanced colorectal cancer. PATIENTS AND METHODS: Patients with previously untreated advanced colorectal cancer received oxaliplatin 130 mg/m² and bevacizumab 7.5 mg/kg every three weeks, capecitabine 850 mg/m² twice daily on days 1-14, and cetuximab at 400 mg/m² load and 250 mg/m² weekly. KRAS, BRAF and PI3K mutation status from paraffin-embedded tumor samples were assessed using real-time polymerase chain reaction. RESULTS: Thirty patients were evaluable for safety and efficacy. One patient had a complete response and 12 patients had a partial response, giving an overall response rate of 43% (95% confidence interval (CI) 25%-63%). Fifteen patients had stable disease. The median time to progression was 10.3 months (95% CI, 6.8-16.3 months). The median overall survival was 18.8 months (95% CI, 14.2-23.7 months). Common grade ≥ 3 non-hematological toxicities were skin rash (37%), sensory neuropathy (27%) and diarrhea (17%). Grade ≥ 3 hematological toxicities were uncommon. Mutations in KRAS, BRAF and PI3K occurred in 34.5%, 10.3% and 10.3% of patients respectively, but did not correlate with treatment outcome. CONCLUSION: The addition of cetuximab to capecitabine, oxaliplatin and bevacizumab did not improve the three-drug regimen activity compared to published data and was associated with significant toxicities requiring frequent dose modifications. KRAS, BRAF, and PI3K mutation status were consistent with published literature, but did not affect outcome in this small study.