The mucoepidermoid carcinoma is a neoplasia that usually occurs at salivary glands, breast, pancreas and gastrointestinal tract. The primary occurrence on thyroid gland is rare and only 33 cases were previously published. Although the majority of cases of mucoepidermoid carcinoma of the thyroid (MECT) show a benign evolution, this paper describes a patient with an aggressive tumor. A literature review over clinical, histopathological, imunohistochemical features and histogenetic origin was discussed.