The size and distribution of intestinal lymph fat particles have been determined in rats fed 80 or 800 mg of various fats (corn oil, lard, margarine, butter, cream, milk). Morphological studies by means of the electron microscope were made either after fixation, inclusion and section, or after fixation and shadow only. VLDL (d < 0. 1 µm) were always abundant; generally, chylomicron diameters were 0.1–0.3 µm; larger ones were sometimes found chiefly after feeding corn oil or margarine. The presence, in the meal, of lipids other than triglycerides and of non-fat components might modify the structure of chylomicron interface.