Malignant tumors of the maxillary sinus are very rare, composing less than 0.2 percent of all human cancers. The diagnosis is often delayed because most of their symptoms occur late when the disease is advanced and treatment results are poor. Recently, owing to the computerized tomography, the extent of invasion of malignant tumors can be evaluated accurately. The authors have reviewed and analyzed 90 cases of histopathologically proved malignant tumors of the maxillary sinus who had been hospitalized in the Department of Otolaryngology of the National Medical Center during last 10 years.