Background: [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) is reported to change the management in 20−56% of patients with recurrent or metastatic colorectal cancer. It is not clear if FDG-PET has a role in all such patients or only a subgroup. The aim of the present study was to assess the influence of FDG-PET on the surgical management of patients with known or suspected colorectal liver metastases. Methods: Patients undergoing FDG-PET for investigation of known or suspected colorectal liver metastases were identified from a South Australian database. Case notes were reviewed retrospectively to determine the influence of FDG-PET findings on patient management. Findings from FDG-PET scanning were compared with findings from conventional diagnostic investigations and operative findings. Results: Overall, in four of 16 patients (25%) management was influenced by FDG-PET findings. FDG-PET altered management in four of eight (50%) patients with non-diagnostic liver lesions on computed tomography (CT) or with elevated carcinoembryonic antigen levels but no liver lesion on CT. In all eight patients with CT diagnosed resectable liver metastases, the addition of FDG-PET did not influence the management. Conclusions: The findings support the use of FDG-PET in the assessment of selected patients with suspected colorectal liver metastases and equivocal findings on conventional diagnostic investigation. ; Benjamin D. Teague, Charles P. Morrison, Fiona G. Court, Venessa T. Chin, Samuel P. Costello, Ian D. Kirkwood and Guy J. Maddern ; The definitive version is available at www.blackwell-synergy.com