Mucoepidermoid carcinoma occurs frequently in the salivary glands but is rare in the thymus. In this paper we provide a literature review on this condition and discuss the clinical data of a case of thymic mucoepidermoid carcinoma (TMEC). Here, we report a case of TMEC in an elderly female patient who showed no obvious symptoms or positive signs for TMEC during her physical examination. However, a chest CT revealed a mass in the anterior mediastinum, which did not appear enhanced upon contrast-enhanced CT. After surgical excision, TMEC was confirmed by histopathologic and immunohistochemical examination. The clinical manifestation of the disease is not obvious, and physical examination is often not enough for diagnosis, hence diagnosis mainly relies on histopathology. Currently, surgery is still the only way to cure TMEC.