Since there exists in the gut a material with glucagon-like immunoreactivity (GLI) which is released during glucose absorption, it was thought that it could have, as does glucagon, insulin-releasing activity, being therefore a component of the enteroinsular axis. In order to study the relationship between insulin and GLI secretion, we have studied both of these responses to an oral glucose load in a series of 18 normal subjects and in another of 8 gas-trectomized patients. It was found that in normal subjects, after oral glucose, plasma GLI increased slightly but consistently from 1.5 ng/ml to 2.3 ng/ml. In the gastrectomized patients, plasma GLI rose more intensively, from 1.7 ng/ml to 5.8 ng/ml. However, in these patients, in spite of the higher blood sugar values and the higher plasma GLI levels during the OGTT, the insulin response was practically identical to that of normal subjects during the first hour of the test. It was significantly higher at only one point (75 min). This relatively lower insulin response, when compared to the elevation of the glycemia, is compatible with a deterioration of the gastroenteroinsular axis caused by the gastrectomy. The fact that GLI hypersecre-tion is not accompanied by a greater insulin response, even in the presence of hyperglycemia, seems to indicate that GLI is not a major intestinal insulin-releasing factor, if indeed it has any such activity.