Treatment options for advanced colorectal have improved substantially in recent years as a number of agents have been developed that have different targets and mechanisms of action. Significant improvements in outcomes have been observed by combining multiple chemotherapeutic agents instead of the single-agent approach. Some debate still remains regarding which combination is most effective and in what order regimens should be given. In addition to cytotoxic chemotherapy drugs, targeted biologic agents have been developed to inhibit tumor angiogenesis, which may hamper the viability of the tumor. There may also be a synergistic effect between antiangiogenic agents and chemotherapy. Regulation of tumor angiogenesis may actually improve blood flow throughout the tumor, which could enhance delivery of chemotherapy through the circulation. One antiangiogenic agent currently approved for the treatment of advanced colorectal cancer is bevacizumab, a monoclonal antibody targeting vascular endothelial growth factor, a ligand known to be important for angiogenesis. The other currently approved biologic agent, cetuximab, targets the epidermal growth factor receptor. The combination of bevacizumab plus cetuximab has a biologic rationale. Randomized trials incorporating combination chemotherapy regimens plus both bevacizumab and cetuximab are currently underway, as are preliminary studies withnovel angiogenesis inhibitors.