For several decades, 5-fluorouracil (5-FU) with or without leucovorin defined the standard of care for the treatment of metastatic colorectal cancer (CRC). The addition of other chemotherapy regimens to 5-FU has improved survival, but often at the expense of increased toxicity. Recent advances in our understanding of the molecular basis of CRC have led to the production of novel targeted agents, such as bevacizumab (Avastin). Bevacizumab is currently approved for the first-line treatment of metastatic CRC and is currently being tested in combination with standard therapies for a range of indications. Phase II/III trials have demonstrated that the addition of bevacizumab to 5-FU-based first-line chemotherapy improves survival, progression-free survival and response rate compared with chemotherapy alone. Combination therapy does not appear to exacerbate side effects known to be associated with the chemotherapy regimen. The most common side effects attributable to bevacizumab therapy include hypertension, proteinuria and bleeding. Although uncommon, gastrointestinal perforation and arterial thromobembolic events are the most serious side effects reported to date. Bevacizumab is currently being evaluated in combination with oxaliplatin (Eloxatin)-based therapies and preliminary data are encouraging. Ongoing trials of bevacizumab in combination with standard first-line chemotherapy regimens will evaluate bevacizumab's potential in a range of cancer types. .