No consensus on the indications for surgical resection of colorectal liver metastases exists. This systematic review has been undertaken to assess the published evidence for its efficacy and safety and to identify prognostic factors. Studies were identified by computerised and hand searches of the literature, scanning references and contacting investigators. The outcome measures were overall survival, disease-free survival, postoperative morbidity and mortality, quality of life and cost effectiveness, and a qualitative summary of the trends across all studies was produced. Only 30 of 529 independent studies met all the eligibility criteria for the review, and data on 30-day mortality and morbidity only were included from a further nine studies. The best available evidence came from prospective case series, but only two studies reported outcomes for all patients undergoing surgery. The remainder reported outcomes for selected groups of patients: those undergoing hepatic resection or those undergoing curative resection. Postoperative mortality rates were generally low (median 2.8%). The majority of studies described only serious postoperative morbidity, the most common being bile leak and associated perihepatic abscess. Approximately 30% of patients remained alive 5 years after resection and around two-thirds of these are disease free. The quality of the majority of published papers was poor and ascertaining the benefits of surgical resection of colorectal hepatic metastases is difficult in the absence of randomised trials. However, it is clear that there is group of patients with liver metastases who may become long-term disease-free survivors following hepatic resection. Such survival is rare in apparently comparable patients who do not have surgical treatment. Further work is needed to more accurately define this group of patients and to determine whether the addition of adjuvant treatments results in improved survival. Colorectal cancer is the third most common cause of cancer death in the UK (Cancer Research UK Information Resource Centre, 2003). Surgery is the treatment of choice for patients with localised disease but over half of all patients will develop metastases. The liver is often the first site of metastatic disease and may be the only site of spread in as many as 30 -40% of patients with advanced disease (Weiss et al, 1986; Hugh et al, 1997a).It has been postulated that because haematogenous spread usually occurs in a stepwise fashion, initially to the liver, with subsequent intrahepatic spread via the portal vein and further spread to the systemic circulation, surgical resection of isolated hepatic metastases from colorectal cancer may be curative.The natural history of metastatic colorectal cancer is variable, with a median survival without treatment of only 8 months (Seymour et al, 1997;Simmonds, 2000). Patients with isolated hepatic metastases have a better prognosis than those with more extensive metastatic disease (Goslin et al, 1982; Lahr et al, 1983;Stangl et al, 1994;Rougier et al, 1995) s...