INTRODUCTION Myositis ossificans traumatica is a pathological condition characterized by the extraskeletal formation of bony tissue, induced by violent or repeated trauma. CASE PRESENTATION A 30-year-old Italian man, after surgical treatment for multiple facial fractures, presented with a progressive limitation of mouth opening. A computed tomography scan showed a significant calcification of the fibers of the left lateral pterygoid muscle. The working diagnosis was myositis ossificans traumatica of the left lateral pterygoid muscle. Surgical excision was suggested but not performed. Our patient underwent physiotherapy treatment resulting not in a complete restoration of mandibular movements but in an acceptable recovery of mouth opening. CONCLUSIONS Myositis ossificans is a rare complication that can be caused by muscle trauma. Therefore, special attention should be paid to surgical trauma. In the present case, surgical excision was considered, in accordance with the literature, and suggested to our patient, but he declined due to the absence of any pain or any significant limitation to his daily life activities. He therefore underwent physiotherapy treatment, in line with our unit's guidelines, resulting not in a complete restoration of mandibular movements but in an acceptable recovery of mouth opening.