Inflammatory myofibroblastic tumors include a diverse group of lesions characterized by inflammatory cell infiltration and variable fibrotic responses. Occurrence in the temporal bone is unusual. We present CT and MR imaging findings of an inflammatory myofibroblastic tumor of the temporal bone in a 26-year-old patient with repeated paroxystic episodes of rotatory vertigo that occurred over a few days. CT and MR imaging revealed a homogeneously enhancing soft-tissue mass of the right mastoid with bone erosion of the tegmen and extensive dural thickening. The mass resembled a malignant tumor, and the patient underwent an extended mastoidectomy through a retroauricular approach. Microscopic examination showed myofibroblastic spindle cells with mixed inflammatory infiltrate, and the pathologic diagnosis was inflammatory myofibroblastic tumor.