The ultrastructure and function of crop and stomach of Haliotis discus hannai Ino were studied w ith histochemical method, electron microscopic observat ion and test for some enzymatic act ivity in vitro. The epithelial cells of the crop and the flat part of the stomach show the ultrastructural features of absorptive cells : microvilli, signs of endocytosis, occurrence of secondary lysosomes and storage of reserve materials ( glycogen and lipid) . These features indicate that absorption of energy..rich substances can occur in the crop and the stomach. The fold part of the stomach is lined by ciliated cells which are involved in sorting and transport of food particles. The intraepithial neurons were observed in the stomach. The epithelial cells of the crop and the stomach show proteinase and non..specific esterase activity by histochemical tests, and show activity of three or four polysaccharide enzymes by test in vitro .