Synovial sarcoma is a relatively rare malignant tumor of the soft tissue. The most common site of occurrence is the extremities, and they rarely occur in the head and neck region. Here, we report on a rare case of synovial sarcoma arising in the parapharyngeal space and parotid region. A 21-year-old man presented with left-sided painless subauricular swelling. Computed tomography (CT) revealed a dumbbell-shaped cystic mass in his left parapharyngeal space and parotid region. Under a tentative diagnosis of cystic lymphangioma, he received percutaneous local injection of OK-432, and the lesion showed drastic reduction temporarily. Seven months after the injection, the subauricular swelling recurred. He then received additional injections of OK-432 on 3 occasion, however, the mass did not decrease but rather increased. CT at this point showed a well-enhanced solid tumor measuring 80 mm in its major axis sitting in the parapharyngeal space and parotid region. The patient eventually underwent transcervical resection of the tumor. Microscopically, the tumor showed spindle cell and glandular epithelial structures and was positively immunoreactive for AE1/AE3, CAM5.2, EMA, bcl-2, calponin, and TLE-1, but not for S-100 and a-smooth muscle actin. In addition, the SYT-SSX1 fusion gene was detected with RT-PCR. From these findings, the tumor was diagnosed as a biphasic synovial sarcoma. The patient received postoperative adjuvant chemoradiotherapy (total 70 Gy+daily carboplatin) combined with thermotherapy. No evidence of recurrence has been seen for a 19-month follow-up period after surgery.