The histologic features of undifferentiated carcinoma of the base of the tongue and lymphoepithelioma, or lymphoepithelial carcinoma, of the nasopharynx are identical and can be considered synonymous. The frequency of undifferentiated nasopharyngeal carcinoma (lymphoepithelioma) located on the base of the tongue is discussed because undifferentiated carcinoma of the base of the tongue is considered to be the same tumor.