Synovial sarcoma is a mesenchymal spindle cell tumor with variable epithelial differentiation. It is unrelated to the synovium as the name might suggest but arises in the soft tissues of the extremities around the knee joints and tendon sheaths. The tumor cells are thought to resemble normal synovial tissue histopathologically, hence named "synovial sarcoma" (SS). Head and neck lesions are less common and oral cavity involvement is extremely rare. Few cases in tongue, soft palate, mandible, buccal mucosa and floor of mouth have been described in the literature. Here, we probably report the first case of primary biphasic SS (BSS) involving gingiva in the retromolar area of the mandible in a 21-year-old male patient.