Solitary bone plasmacytoma belongs to a group of lymphoproliferative clinical disorders typified by clonal proliferation of plasma cells. Solitary plasmacytoma typically involves a single bone or extramedullary site. It commonly occurs in the vertebrae or thorax, and rarely involves the mandible. The aim of this report is to present a rare case of solitary plasmacytoma of the jaws mimicking periodontal disease. A solitary plasmacytoma involving the right mandibular ramus/angle was observed in a 60-year-old woman, which was a coincidental finding following persistent excessive post-extraction hemorrhage. The patient was referred for radiotherapy, and subsequent follow up has been uneventful. Although solitary plasmacytoma of the mandible is a rarity, it may occur nonetheless. It may mimic periodontal disease; hence clinicians should have a high index of suspicion when managing patients.