A case of large cell neuroendocrine carcinoma (LCNEC) of the tongue base is described. It was characterized by solid tumor nests with central necrosis and rosette formation resembling basaloid squamous cell carcinoma. Immunohistochemical examination revealed that this tumor had neuroendocrine differentiation. It was diagnosed as LCNEC of the tongue base. Pulmonary LCNEC is a well-established entity, but LCNEC also occurs in other organs. This is the first report of mucosal LCNEC in the oral cavity. Basal cells in the normal squamous epithelium around the tumor indicated positivity for neural cell adhesion molecule and N-cadherin. These cells were considered neuroendocrine-related cells in the lingual squamous epithelium, which are related to the tumorigenesis of mucosal LCNEC in the tongue base.