Low-grade myofibroblastic sarcoma is a malignant tumour from myofibroblasts, which has only recently become clearly defined. It represents a rare entity developing in the soft tissues of the head and neck. About 20 cases have been reported in the oral cavity, especially in the tongue and bone, while gingiva as the primary site has been described only once to date. Diagnostic methods include histology and immunohistochemistry. The present report concerns a case of a 37-year-old man who presented with a persistent gingival ulcerated swelling that was interpreted for a long time as a gingival epulis. A low-grade myofibrosarcoma was diagnosed and the patient underwent a segmental osteotomy of the mandibular symphisys for complete excision. There was no sign of recurrence or metastatic disease during the 18-month postoperative period.