The recent successful development of monoclonal antibodies that target key components of biological pathways has expanded the armamentarium of treatment options for patients with colorectal cancer (CRC). In particular, the epidermal growth factor receptor (EGFR), a tyrosine kinase growth factor receptor involved in CRC development and progression, is exploited by the newest monoclonal antibody that is available for use in CRC patients. Cetuximab, the first chimeric monoclonal antibody, which has been generated against the EGFR, is currently registered in USA, Europe and worldwide, in combination with irinotecan in the treatment of metastatic CRC patients who have progressed on irinotecan containing chemotherapy. Cetuximab is well tolerated and does not exacerbate the toxicity of concomitant chemotherapy. Furthermore, a series of phase III clinical trials are currently evaluating the combination of cetuximab with standard chemotherapy regimens in the first-line treatment chemotherapy-naïve patients with metastatic CRC.