An in vitro system which uses perifused pieces from the antrum of rat stomach has been used to study the effect of dihydrosomatostatin on gastrin release. The gastrin concentration in fractions of the perfusate was measured by radioimmunoassay. Dihydrosomatostatin (2 x 10-7M) had no effect on basal gastrin levels but virtually abolished the biphasic response seen with argine stimulation. The study demonstrates close functional similarities between G cells and pancreatic islet cells.