Adenoid cystic carcinoma (ACC) is a rare malignant tumor, mostly involving the minor salivary glands. Herein, we present a case of ACC in a 43-year-old man with symptoms of dental abscess as the initial presentation of the tumor. In spiral computed tomography (CT) scan, soft tissue mass with the erosion of maxillary sinus wall on the right side of the alveolar ridge was evident. Histopathological examination of the excised tumor with immunohistochemical studies (C-kit, Vimentin, pan-cytokeratin, p53, p63, and ki67 positive reaction) confirmed grade 2 ACC in the maxillary sinus. The patient underwent hemimaxillectomy and right-neck dissection. Due to the extension of tumor cells excessively into the surrounding tissues and involvement of orbital bone, complete and total resection of the tumor with safe margins could not be done. After surgery, adjuvant radiotherapy was considered for the patient. At the end of treatment, the patient lost his eye vision. Seventeen months from initial diagnosis, he was still alive without lung or distant metastasis.