Forty-three consecutive cases of mucoepidermoid carcinoma of the major and minor salivary glands were studied to evaluate the influence of the following parameters on prognosis: age, sex, location, local extension, mitotic counts, vascular invasion, grade of differentiation, and nuclear DNA ploidy assessed by image cytometry. The age of the patients ranged between 7 and 84 years. Twenty-eight patients were male and 15 female. Thirty-five tumors were in the major salivary glands and 8 in the minor glands of the oral cavity. According to Healey's criteria, 14 tumors were classified as grade 1, 17 as grade 2, and 12 as grade 3 and, according to the 1990 World Health Organization proposal, 17 tumors were classified as low-grade and 26 as high-grade neoplasms. Image cytophotometric DNA analysis revealed 15 euploid and 6 aneuploid tumors. The range of the follow-up study was 3-156 months (mean, 40.7 months). The 5- year actuarial survival for each of the above-cited parameters was: 100% and 59.1 % for patients aged less than 20 and over 55 years, respectively; 49.6% for male and 85.7% for female patients; 61.3% for major gland and 73.3% for minor gland tumors; 100% and 57.5% for intraglandular and extraglandular major salivary gland neo plasms, respectively; 46.2% for cases with high mitotic rate and 83.1% for those with low mitotic rate; 38.7% and 81.6% for tumors respectively with and without vascular invasion; 100% for grade 1 and 64.7% for grade 2; none of the patients with grade 3 neoplasms were alive at 5 years. Survival was of 100% for low-grade and 40.7% for high-grade tumors. Survival was 92.8% for euploid tumors and 61.3% for the aneuploid ones. In conclusion, survival of patients with mucoepidermoid carcinoma is significantly related to the histological grade of differentiation, the mitotic count, the presence of vascular invasion and the DNA ploidy of the tumor cells. Int J Surg Pathol 1(1):3-12, 1993