Brown tumors are uncommon focal giant cell lesions. They usually occur in hyperparathyroidism. Brown tumors are resulting from abnormal bone metabolism in hyperparathyroidism. We report that a 28-year-old woman who initially presented with left facial pain for three months. First, the patient accepted medical treatment but the symptom was not improved. MRI was arranged for the patient and the report showed a mass in the left maxillary sinus. Tumor biopsy was suggested at Department of Otorhinolaryngology, Head and Neck Surgery. The pathology showed a giant cell granulation. So, the patient was arranged to operate and the tumor was excised by endoscopy. The pathology showed brown tumors. The thyroid echo showed a 3.6×1.2×1.2 cm parathyroid mass. The patient underwent parathyroidectomy. Postoperatively, her symptoms had improved and no other complications occurred.