Globules or particles of material, 50 Å to 1000 Å in diameter, stained with Pb++ to become dense, occurred between, on, or within the microvilli of the absorptive cells of the proximal jejunum of rats which had been fasted for 48 hours and fed corn oil one hour before sacrifice. This material was demonstrable in tissues fixed in glutaraldehyde, osmium tetroxide, or both fixatives providing Pb++ staining occurred. No or very little stainable material was present in fasted rats. These findings were correlated with in vitro studies on negatively stained or Pb++ stained solutions of micelles. The absorption of particulate lipid by the microvilli of the epithelial cells of the small intestine is discussed.