A new type of cytoplasmic granules was demonstrated with the electron microscope in a substantial percentage of absorptive cells in the small intestine of standard-fed, fasted and oil-fed CFW/L1 mice, and extremely rarely in standard-fed Balb/C mice. The granules appeared as the accumulations of electron-dense material within the distended cisternae of the rough endoplasmic reticulum. Most of the intracisternal granules were situated in the basal part of the cell, close to the nucleus. The diameter of the granules ranged from 0.24/micron to 0.96/micron.