Gastric motility and pyloric contractility were studied in laparotomized cats under chloralose anaesthesia by recording the intragastric volume and changes in an applied constant transpyloric flow of body-warm saline. Unilateralefferent electrical stimulation of the cervical vagi resulted in a prompt gastric contraction and a delayed pyloric contraction. In one third of the animals abiphasic pyloric motor response, consisting of a short period of increased flow preceding the longlasting decrease or cessation of the flow was observed. Afteratropine (0.2 mg/kg b.w.) the vagal nerve stimulation resulted in agastric relaxation, while the biphasic pyloric motor response was even more pronounced, with a significantly longer latency of the contractile phase. Addition ofguanethidine (2 mg/kg b.w.) did not affect these motor responses. Afterhexamethonium (25 mg/kg i.v. and 50±10 mg per kg i.a. b.w.) the stimulation procedure still resulted in a slight gastric relaxation, while the pyloric contraction was effectively blocked. However, the relaxatory phase required theaddition of atropine to become antagonized indicating separate transmission mechanisms for the relaxatory and contractile components of the pyloric motor response at efferent vagal stimulation.