Our aim was to investigate the existence of an inhibitory innervation at the gastroduodenal junction (GDJ) in the whole animal. Motility induced by vagal stimulation was monitored with strain force transducers on the gastric antrum, pylorus and duodenum. The experiments were carried out in two phases: the control phase following vagotomy (TV), and the treated phase where atropine sulfate (1 mg/Kg) was injected intravenously (TV+A). After TV, antral, pyloric and duodenal contractile activity was significantly increased (P less than 0.01) during the period of vagal stimulation. After (TV+A), spontaneous activity in the antrum and duodenum was abolished and vagal stimulation did not increase motility in these organs. Spontaneous pyloric activity present after atropine administration was inhibited by stimulation, and a concomitant relaxation of the pylorus was also demonstrated. Following the termination of the stimulus, a significant increase in contractions was noted on the pylorus. These experiments demonstrate the existence of an atropine-resistant inhibitory innervation at the GDJ in the anesthetized dog.