Although a lot of food-derived peptides have been applied for medical use and therapeutic nutrition, the function of feed-derived peptides on nutritional physiology in chickens has not been clarified so far. Our previous study revealed that wheat gluten digested by trypsin could enhance the absorption of amino acids from small intestine. In the present study, we studied the influence of trypsin-digested wheat gluten peptides with different molecular weight (MW) on the intestinal absorption of amino acids in chickens. Wheat gluten was digested by trypsin and fractionated by using the ultrafiltration membrane. Wheat gluten peptides were divided into 3 fractions with different MW; MW more than 10,000, MW 3,000-10,000 and MW less than 3,000. Phosphate buffered saline and whole wheat gluten digesta were used as negative and positive controls, respectively. All of wheat gluten peptides were mixed with 2.5M glucose-10 mM amino acid solution and administrated into the crop with a stomach tube. At 20 min after oral administration, blood samples were taken from mesenteric vein. Plasma amino acid concentration was determined using an automatic amino acid analyzer. The peptide fraction with MW more than 10,000 increased the intestinal absorption of phenylalanine and proline. The peptide fraction with MW 3,000-10,000 increased the intestinal absorption of proline. These results suggest that wheat gluten peptide with high MW might have the potency to enhance the absorption of aromatic amino acids from small intestine of young chickens.