Mucoepidermoid carcinomas in mammary glands represent 0.3% of all breast tumors. Features of salivary gland mucoepidermoid carcinoma have been used in studies concerning mucoepidermoid carcinomas of the breast because both share similar morphologic and molecular features. We report a case of primary mucoepidermoid carcinoma of the breast with an immunohistochemistry staining panel. We verified that MUC5AC occurs in more than 50% of high-grade tumors, and MUC1 correlates with shorter disease-free survival. The comparative analysis of mucin profiles may provide further insights into the clinical behavior of these tumors.