Cases of idiopathic gingival enlargement are so infrequent that the etiology and treatment are subjects of discussion. The case of a 49-year-old woman who presented with a rapidly diffuse enlargement of gingiva, clusters of patches on the buccal mucosa, and a furry-coated tongue within 2 months is reported. Results of various laboratory investigations and additional tests, such as the antineutrophil cytoplasmic antibodies (ANCA) and autoantibody to nuclear antigen (ANA) tests, were all negative. Histopathologic examination showed hyperplasia of inflammatory granulation tissues. Oral steroid therapy was effective. Although cases of multiple hyperplasia of inflammatory granulation in the oral cavity are very rare, clinicians should be aware of such cases and understand the efforts to further delineate the etiology, the management, and the prevention of the recurrence of this condition. Keywords: etiologic factors, hyperplasia, idiopathic, inflammatory granulation, oral lesions, therapy