With the advent of effective drug therapy, tuberculous lesions of the oral cavity have become so rare that they are frequently forgotten. Primary gingival tuberculosis is extremely rare and usually manifests as ulcer. We report the first case of primary tuberculosis manifesting as gingival enlargement, which was the only presenting sign of tuberculosis. Diagnosis was based on histopathology (hematoxin and eosin staining), complete blood count, polymerase chain reaction assay and immunologic investigation with the detection of antibodies against Mycobacterium tuberculosis. The possibility of gingival enlargement due to drugs, leukemia, fungus and sarcoidosis was ruled out. Antituberculous therapy over 6 months was followed by surgical excision of the residual enlargement under local anesthesia. After 1-year follow-up there was no recurrence of the disease. This case emphasizes the need for dentists to include tuberculosis in the differential diagnosis of gingival enlargement so that they may play a role in its early detection.