Abstract: The esophagus of disk abalone, Haliotis discus hannai Ino, was studied with histo logical and histochemical methods, scanning and transmission electron microscopic observation, and test s for some enzymat ic activity. The esophagus is divided into anterior, mid and posterior partitions. The mid esophagus is again divisible into two structurally and functionally distinct regions, a central food channel and two lateral pouches. The epithelium of the esophagus consists of five types of cells, ciliated columnar cell, mucous cell, granular gland cell, cell w ith microvilli and secretory cell. Ciliated columnar cells participate mainly in transport of food and secretion, and show structural features of absorptive cells. Mucous cells secrete neutral and acid mucopolysaccharide. Granular gland cells contain a large number of secretory granules. Cells w ith microvilli also show the features of absorptive cells. Secretory cells, the main glandular cells in the lateral pouches, show strong activity of proteinase and non-specific esterase. They may secrete digestive enzymes by the apocrine. The secretory cells may also participate in absorption and intracellular digestion of food. The epithelium of the mid esophagus shows activity of three plant polysaccharide enzymes by test s in vitro .