Primary pulmonary synovial sarcoma is an extremely rare tumor with an unknown cause. The diagnosis is established after other primary lung malignancies or metastatic extrathoracic sarcoma have been excluded. We report the case of a 69-year-old man who presented with a well-defined mass in the right upper lobe on a chest X-ray. A video-assisted thoracoscopic surgery (VATS) right upper lobectomy was performed. Immunohistochemically, neoplastic cells were positive for vimentin, CD56 and Bcl-2, and focally positive for CD99, epithelial membrane antigen and cytokeratin 7 and 19. The cytogenetic study revealed a SYT genetic reassortment. So, the final pathological diagnosis was primary pulmonary synovial sarcoma.