The plasma response of various counterregulatory hormones was measured after an oral glucose tolerance test in 19 normal subjects. Significant elevations in plasma epinephrine (P less than 0.05) and human GH (P less than 0.05) were observed late in the course of the oral glucose tolerance test coincident with the fall in plasma glucose. Plasma norepinephrine, glucagon, and cortisol levels did not change during the latter phase of the test. The elevations in plasma human GH and epinephrine levels were unrelated to either absolute hypoglycemia or to clinical symptoms of hypoglycemia. These data suggest a possible role for adrenergic mechanisms in glucose counterregulation under physiological conditions.