Follicular dendritic cell tumors are extremely rare. Only 17 cases have been previously described in the literature, and only three of them involved primary tumours of the oral cavity. We describe a new case of the latter, which occurred in a 51-year-old man who sought evaluation for a painless enlargement of his left palatine tonsil. The tonsil was excised, and histologic examination revealed that the tumor was a primary sarcoma that had arisen from the dendritic reticulum cells of the palatine tonsil. Postoperatively, the tumor site was treated with percutaneous irradiation (total dose: 70 Gy). After more than 5 years of follow-up, the patient showed no evidence of recurrence. We also discuss the salient features of the immunohistochemical examination.