A thirty year experience with 367 patients who had mucoepidermoid carcinoma of salivary origin is reviewed. The tumor arose in the parotid gland in 254 patients. The presentation and clinical course depended significantly on whether the tumor was low, intermediate, or high grade in histologic appearance. Metastasis and tumor-related death were occasionally noted in patients with low grade lesions, suggesting that even the most innocuous-appearing mucoepidermoid tumor has malignant potential. Significant correlation was demonstrated between the clinical stage of a tumor and its histologic appearance. Stage I tumors were usually of low histologic grade and were effectively controlled by conservative surgical procedures. Radical operations were often ineffective in patients with stage III tumors, most of which proved to be of high histologic grade. Considering the poor prognosis in the latter patients, adjunctive therapy in the form of postoperative external radiation seems indicated. In our experience, "cure" rates in patients who had intermediate or high grade lesions varied widely, depending upon the stage of the tumor. This strongly suggests that therapeutic decisions should not be based on histologic appearance alone.