The presence, extent and localization of distant metastases are key prognostic factors in breast cancer patients and play a central role in therapeutic decision making. The aim of this study was to compare the diagnostic performance of positron emission tomography using 2-fluorine-18fluoro-2-deoxy-D-glucose (FDG–PET) with that of computed tomography (CT) and conventional imaging including chest radiography, abdominal ultrasound and bone scintigraphy. A total of 119 consecutive patients with newly diagnosed locally advanced disease (n = 69) or previous history of breast cancer (n = 50) who had clinical suspicion of metastatic disease underwent FDG–PET, CT and conventional imaging procedures. Imaging results were retrospectively compared with histopathology and clinical follow-up which served as a reference standard. FDG–PET detected distant metastases with a sensitivity of 87% and a specificity of 83%. In contrast, the sensitivity and specificity of combined conventional imaging procedures were 43% and 98%, respectively. CT revealed a sensitivity of 83% and a specificity of 85%. In breast cancer, FDG–PET is superior to conventional imaging procedures for detection of distant metastases. Although FDG–PET and CT provided similar diagnostic accuracy, the information was often found to be complementary. With increasing availability of FDG–PET/CT, prospective studies are needed to determine whether it could potentially replace the array of conventional imaging procedures used today.