Many studies have pointed out the role of (18)F-FDG PET/CT (or (18)F-FDG PET) in patients with clinical stage III or II breast cancer. (18)F-FDG PET/CT might advantageously replace other staging procedures, such as bone scanning and possibly contrast-enhanced CT of the thorax or abdomen-pelvis. We discuss the findings, locoregional or distant, that can be expected in different categories of breast cancer and their impact on prognosis and management. We also discuss the role of (18)F-FDG PET/CT in restaging and how (18)F-FDG PET/CT compares with conventional techniques in restaging for patients with suspected disease recurrence. We conclude with some recommendations for clinical practice and future research.