Background: Salivary gland tumors are rare and with different malignant potential. Immunohistochemistry is useful, especially Ki67, a marker of cell proliferation, for its prognostic information. On the other side, the mucin MUC-1 is overexpressed and loses its exclusively apical membranous localization and is aberrantly glycosylated in mucoepidermoid carcinoma of salivary glands. In the present work, we investigated the quantitative expression of tumor proliferative index and localization and overexpression of MUC-1 in the mucoepidermoid carcinoma of the human salivary glands, not studied is these organs, to determine their relationship with the histological grade and prognosis. Methods: H/E staining and immunohistochemistry with MUC-1 and Ki67 antibodies was performed on 10 cases. Results: The markings of the mucoepidermoid carcinoma depended on the histological grade; in low- grade tumors with MUC-1 only 10 to 25% of the cells were labeled, in contrast to high- grade tumors, with 75 to 90% labeled cells. They also differed in cell proliferation; in the low-grade tumors was 15% and in high-grade tumors it was greater than 30%. Conclusion: MUC-1 overexpression is significantly higher in high-grade mucoepidermoid carcinoma, as is Ki67 marking, results that are associated with tumor prognosis.