Granulocytic sarcoma (GS) is a localized infiltrate of immature granulocytes in an extramedullary site. This lesion is most frequently associated with leukemia, but can occur associated with others myeloproliferative disorders.GS can affect virtually any part of the body, but lesions in the oral cavity are rare, with only 37 cases described.Case Description: We present a rare case of GS in a 23-year-old female, with a prior history of acute myeloid leukemia, presenting with a solitary mandibular swelling in the region of the erupting 3rd lower left molar. After biopsy, conventional immunohistochemical stains were positive for CD45 (hematological marker) and myeloid markers, such as myeloperoxidase, and CD68, demonstrating myeloid lineage with monocytic cells differentiation, suggesting the diagnosis of GS associated to Acute Myeloid Leukemia (AML-M5).Clinical implication: Although GS is a rare tumor in oral cavity, and its diagnosis is usually difficult, the clinician must know about its existence to make differential diagnosis.