18FDG PET/CT is the standard of care for nodal staging of lung cancer. its role in the staging of breast cancer is more controversial. This technique suffers from lack of sensitivity for certain subsets of breast tumors (e.g low FDG uptake in case of lobular carcinoma and/or low grade tumors) and its limited spatial resolution (5-6mm). It cannot replace the sentinel node biopsy. However, when considering large or locally advanced breast cancer, or inflammatory cancer, several studies have shown that PET/CT performs better than conventional imaging. In these patients, PET/CT may identify high level axillary as well as extra-axillary involvement (supraclavicular, internal mammary lymph nodes). Thus, the data provided by PET may modify the initial planned local management (surgery and radiotherapy). In addition, PET/CT is also effective for detecting distant metastases. In conclusion, PET/CT is not indicated in the initial staging of breast cancer of small size but it should be considered in the management of patients with more advanced tumors.