The possible role of gastrin on TSH, ACTH and cortisol secretion was evaluated by intravenous administration of pentagastrin, the carboxyl-terminal tetrapeptide of gastrin (0.5 µg/kg b.w.) into 12 healthy subjects. Pentagastrin produced a significant rise in plasma ACTH and cortisol levels but did not alter TSH basal release. These preliminary results suggest that gastrin can influence basal activity of ACTH-cortisol axis. However, further investigation is required to determine its physiological role and mechanisms of action.