Radioactive seed localization (RSL) is an increasingly utilized and effective approach to surgical excision of radiographically identified lesions in the breast. This approach has been reported to be at least as convenient to the patient, radiologist, and surgeon as the standard wire localized approach but with the considerable added benefit of a lower positive margin rate in some studies. To date, there is little information in the published medical literature concerning the optimal handling of these specimens in the pathology laboratory. The US Nuclear Regulatory Commission and its Agreement States oversee the use of radioactive materials in clinical practice and provide guidelines for the performance of RSL procedures, including the safe handling of radioactive seeds. The RSL procedure involves multiple departments, and a robust process should be in place to ensure appropriate accountability, seed tracking, and minimal radiation exposure to staff. This article describes how to properly and safely handle RSL breast specimens, including regulation requirements, specimen labeling and receipt, specimen dissection, protective wear, and seed retrieval, transport, and disposal.