Tuberculous osteomyelitis of mandible is an extremely rare condition and forgotten entity. Tuberculosis is a specific granulomatous infectious disease and a major cause of death in developing countries. Involvement of the periodontium has seldomly been reported in the recent literature. The diagnosis was based on patient’s medical and dental history, clinical and radiographic examination, blood investigation, histopathologic examination of the tissue specimen. Antitubercular chemotherapy along with sequestrectomy and decortication are the treatment of choice for tuberculous osteomyelitic lesions affecting periodontium. We report a case of tuberculous osteomyelitis of mandible affecting periodontium leading to attachment loss and bone defect.