The jejunal absorption of either an elemental solution (amino acids, glucose and glucose oligosaccharides), or of nonelemental diet (chicken meat, egg-yolk powder, soya flour, glucose, saccharose, maltose and dextrin maltose, corn and wheat oils) were compared in 25 healthy subjects by the technique of intestinal perfusion with a three-lumen tube. The test solutions were perfused just beyond the ligament of Treitz. The samples were collected 35, 70 and 105 cm below the infusion point. The nitrogen load, in the form of amino acids, did not increase the absorption efficiency. The rate of lipid digestion absorption is high. In a small segment of jejunum, the absorption increased the nutritional imbalance of the elemental diet 1 m below the infusion point, the flow rate in the lumen was similar for the two solutions and higher than the initial flow rate; the absorption, in terms of calories, is similar for the two solutions.