IgG4-related disease is a systemic, multifocal, immune-mediated disorder that can affect multiple organs and may present as a tumor, with rare cases described in the maxillofacial region. A female patient, 53 years old, presenting tumor-like mass in the right mandibular region. Magnetic resonance imaging suggested well circumscribed nodular lesion adjacent to the branch / body of the mandible, extending posteriorly to the masseter muscle. During the surgical procedure of excision, a lesion was observed adhering to the right masseter muscle, but it was possible to remove it completely. Histopathological and immunehistochemical analysis suggested diagnosis of IgG4-related disease, furthermore, IgG4 serum count was increased. Actually, the patient continues on periodical followups in our service and by other specialties. Can be concluded that precise diagnosis of this pathology depends on many factors, being challenging and the treatment involves multidisciplinary evaluation due to the possibility of involvement of several other organs. KEY WORDS: IgG4; IgG4-related disease; Tumor FONSECA, V. J.; MANZANO DE MORAES, A. C.; OLATE, S.; ASPRINO, L. & DE MORAES, M. Immunoglobulin G4-Related disease of the maxillofacial region. A Rare Case.