To test the direct influence of myoinositol on insulin release, rat pancreases were perfused with a medium containing glucose (6.6 mmol/L) or glucose with myoinositol at concentrations of 0.15, 1.55 or 15.5 mmol/L. Myoinositol at the lowest concentration was without effect. At concentrations of 1.55 and 15.5 mmol/L inositol significantly augmented insulin secretion; the total amount of insulin released during perfusions (30 min) with this compound was 508 and 478 µU, respectively vs 353 µU secreted during the same time of perfusion without inositol. It seems quite possible that inositol may augment insulin secretion by formation of ATP, inositol phospholipids or inositol hexaphosphate.