Purpose: 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. Patients and Methods: 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. Results: 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. Conclusion: 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.641115921597