The influence of a short-term treatment with acetylsalicylic acid (ASA 3,2 g/daily), an inhibitor of endogenous prostaglandin synthesis, on plasma glucose, glucagon and growth hormone responses to insulin-induced hypoglycemia, has been investigated in seven subjects. ASA caused a slight but significant reduction in basal glucose levels, but did not alter the pattern of glucagon and growth hormone secretion following hypoglycemia. On the basis of these results, it is hypothesized that endogenous prostaglandins are not implicated in the response of pancreatic alfa-cell to hypoglycemia.