The structure of the lingual papillae and the ultrastructure of the surface of the lingual dorsal epithelial cells of squirrel monkeys were observed by scanning electron microscopy. Filiform papillae were distributed over the entire dorsal surface of the tongue, except for the radix zone. Fungiform papillae were scattered among these filiform papillae. In the middle of the posterior end of the lingual body, a single vallate papilla was located. Higher magnification of the lingual dorsal epithelium revealed that prominent microridges and elevated intercellular borders occurred widely in the basofrontal area of the filiform papillae, interpapillar area and lingual radix zone. On the surface of the upper part of the filiform papillae, fine pits and hollows were observed. Indistinct microridges were distributed over the surface of the fungiform papillae.