The aim of this study was to analyze the clinicopathologic characteristics of all cases of adenoid cystic carcinoma (ACC) and mucoepidermoid carcinoma (MEC) arising in the maxillary sinuses treated in a single institution. From 1953 to 1997, 18 ACCs and 7 MECs from the maxillary sinus were studied. Clinical data were obtained from the medical records and microscopic slides were reviewed. Mean age was 45.9 years (range, 13 to 77 years) and TNM staging revealed 88.9% of ACCs at advanced clinical stages, while 57.1% of the MECs were initial clinical stages. Surgery combined with radiotherapy was the most common treatment. Follow-up showed 88.8% of ACC patients died from the tumor, while 42.8% of patients with MEC are alive without disease. Maxillary sinus ACC and MEC are uncommon tumors and a patient's prognosis depends on the clinical stage and histologic type; MEC has shown a better outcome.641592-7