Oncocytic neoplasms are tumors composed of oncocytes (i.e., epithelial cells with a large cytoplasm that is rich in mitochondria). Most cases are benign and originate from the major salivary glands, while the minor salivary glands are rarely involved. Occurrence of oncocytic carcinoma (or malignant oncocytoma) within the sinonasal tract is an unusual event. We report a rare case of maxillary sinus oncocytic carcinoma occurring in a 45-year-old male. Biopsy was consistent with an unspecified salivary gland neoplasm. The patient underwent total maxillectomy through a lateral rhinotomic approach; hard palate reconstruction with temporal myofascial flap was performed. Definitive histology was consistent with oncocytic carcinoma. Due to the local extension of the lesion, postoperative radiotherapy (60 Gy) was delivered. Three years after surgery, the patient is free from disease. A brief analysis of the literature was also accomplished in order to discuss treatment options and prognosis of this unusual neoplasm.