Abstract A rare case of an intraoral glomus tumor on the ventral surface of the tongue was studied by light and electron microscopy. With light microscopy, the tumor was composed of dilated vascular channels surrounded by “epithelioid” glomus cells exhibiting large round nuclei and abundant eosinophilic cytoplasm. Bodian stains showed significant staining for nerve fibers among the tumor cells. Electron microscopic study demonstrated that the tumor cells had ultrastructural features which were similar to both smooth muscle cells and endothelial cells, suggesting that a “transitional” cell may give rise to glomus tumor. The literature on oral glomus tumors is briefly reviewed.