Mucoepidermoid carcinoma of the salivary glands: a reappraisal of the influence of tumor differentiation on prognosis. Thirty-nine cases of mucoepidermoid carcinoma of the salivary glands were reviewed for a reappraisal of the influence of the grade of differentiation on the outcome of the disease. The age of the patients ranged between 7 and 84 years. Fifteen patients were females and 24 males. The tumors were located at the parotid gland (n = 30), the submaxillary gland (n = 1), the soft palate (n = 5) and the oral mucosa NOS (n = 3). At presentation 4 tumors were intraglandular and 35 extraglandular; three patients had lymph node metastases and one patient lung metastases. The grade of differentiation was assessed using the criteria of Healey et al. Twelve tumors were classified as grade I, 17 as grade II, and 10 as grade III. Follow-up information was obtained with a duration of 5-144 months (mean 44.7 months). Six cases recurred locally and 5 developed metastases. Five years cumulative survival was 100% for grade I, 70.1% for grade II, and 47.2% for grade III. The results point to the usefulness of the assessment of the grade of differentiation as a guide to anticipate the outcome of the disease. 