Inflammatory myofibroblastic tumor is a rare lesion composed of myofibroblastic spindle cells accompanied by inflammatory infiltrate. The objective of this paper is to report an uncommon case of inflammatory myofibroblastic tumor located in the alveolar mucosa of the mandible. A 33-year-old male presented an asymptomatic tumoral lesion, firm, pedunculated, pink-colored, covered by smooth mucosa, with focal ulceration, measuring 30x20x20 mm, located in the left posterior alveolar mucosa. Clinical diagnosis was soft tissue tumor. An excisional biopsy was made. Microscopic examination showed compact fascicular spindle cells proliferation with a diffuse inflammatory infiltrate of plasma cells, lymphocytes, and eosinophils. Large ganglion-like cells were observed. The lesional cells were immunopos-itive to vimentin, a-smooth muscle actin, muscle specific actin, and CD68. Negative immunostain was observed to S-100, Bcl-2, Ki-67, desmin, CD34, and cytokeratin. A diagnosis of inflammatory myofibroblastic tumor was performed. After 28 months of follow-up there was no recurrence. Although no evidence of oral inflammatory myofibroblastic tumor recurrence or malignant transformation has been reported, it has been observed that in inflammatory myofibroblastic tumor of other regions a prolonged follow-up is necessary after surgical excision.