The hypothesis was made of an increased oxidation of fatty acids (FFA) and a decrease of their esterification rate contributing to the islet secretory defect during starvation. 2-Bromostearate (BrS), a FFA-oxidation inhibitor, was therefore tested on the islet secretion of insulin, glucagon and somatostatin stimulated by glucose or palmitate under fasted or fed conditions. Starvation for 48 h blocked both the glucose-induced stimulation and inhibition of insulin and somatostatin and the glucagon secretion. BrS completely restored the insulin response and stimulated both somatostatin and glucagon-basal release, the latter inhibition by glucose being partially recovered. Palmitate transient stimulation of insulin and somatostatin and inhibition of glucagon release was turned into a sustained increase in all three cases by addition of BrS. The potentiation by BrS of palmitate secretory effects in "fed" islets and of hormone release in "fasted" islets, apparently suggest that inhibition of FFA-oxidation may play a role in the regulation of islet secretion.