The endocrine cells in te normal antral mucosa of the human stomach were examined by the electron microscope. According to their fine structural characteristics, they were classified into the following five types. 1) Cell-type Ⅱ is triangular in shape. The granules are round and vary in diameter (300-600mμ) and in electron density. 2) Cell-type Ⅲ is triangular in form and has many grnules (130mμ in diameter) with high electron density. These granules are characterized by their uniform size and homogeneous appearance. 3) Cell-type Ⅳ contains a prominent endoplasmic reticulum in the supranuclear region. These kinds of granules are recognizable in the basal part: smaller ones (100-200mμ), which are dense, larger ones (400mμ) which are pale and another larger ones (400mμ) which are empty-looking. 4) Cell-type Ⅴis contact with the glandular lumen and contains numerous secretory granules with various densities. 5) Cell-type Ⅵ is oval in shape and characterized by small granules (100-150mμ) with moderate density, localized in the basal region. This cell type seems to have some features of an immature endocrine cells.