The achromatic epithelial cells (AEC), whose cellular materials remain unstained by several stains, e. g., H.E, PAS, Alcian blue, Orange G Anilin blue and Mucicarmin, are detected in the intestinal mucous epithelium of the Iar: Wistar Imamichi rat from the 19th day of gestation to the 21st day after birth. The results of light microscopic and transmission electron microscopic observations suggest that the rats AEC are equivalent to the previously reported vacuolar cells (VC) in cattle and in mice. The present paper describes that rat intestinal AEC appear first in the small intestine, and spread progressively toward the anal direction, while they disappear first in the cecum, and finally disappear at the ileum and the colon 22 days after birth.