Granuloma formation is a specific type of chronic inflammation initiated by infectious and noninfectious agents with an aggregation of multinucleated giant cells. Foreign body giant cells (FBGCs) most commonly observed at the tissue/material interface where the size of foreign particulate is too large to permit macrophage phagocytosis. In this context, adherent macrophages and FBGCs constitute the foreign body reaction. Foreign-body giant cell granulomas have been reported to cause clinical symptoms from months to decades after a surgical procedure and can present with a variety of symptoms, usually on the basis of location. Foreign-body giant cell granulomas in the mandible are rare lesions, here we report a case of FBGC granuloma in the mandible that developed after endodontic treatment.