The effect of ingestion of amino acids (Vamin N), glucose, and fat (Intralipid) on the concentration of neurotensin‐like immunoreactivity (NTLI) in plasma was determined in 6 healthy male volunteers. After ingestion of Intralipid (55 ml, 200 mg·ml^‐1) there was a significant increase in the plasma concentration of NTLI. The calculated integrated total NTLI response (6.7 ± 2.5 nM over 180 min) was statistically significant. Although isocaloric amounts of Vamin and glucose also increased the plasma concentration of NTLI, these increases were not statistically significant. The data indicate that fat is an important stimulus for the release of NTLI from the small intestine. It is suggested that neurotensin, or a metabolite, in blood may be a hormone involved in the postprandial inhibition of gastric motility and gastric acid secretion elicited from the small intestine.