Similar to the previously discussed approved applications in oncology, FDGPET in breast cancer has demonstrated superior diagnostic accuracy compared with conventional anatomic imaging for the detection of distant metastases. This increased accuracy in lesion detection has translated into improved staging, especially in cases with a high clinical suspicion or pre-test probability of distant metastases. In addition to staging and restaging, another application for FDGPET covered by Medicare is in the evaluation of tumor response to therapy. This chapter briefly reviews the basic classification and imaging aspects of breast cancer; describes the currently approved clinical indications, as defined by the Center for Medicare and Medicaid Services (CMS); and discusses the accuracy, strengths, and limitations of FDG-PET.