We have investigated the actions of various prostanoid receptor agonists on an isolated preparation of the ferret cervical vagus using a grease-gap extracellular recording technique. The potency ranking for depolarization was BW245C (5-(6-carboxyhexyl)-1-(3-cyclohexyl-3-hydroxypropyl) hydantoin; DP-selective, EC 5 0 =0.14 μM)>prostaglandin E 2 (nonselective EP agonist)>U-46619 (11α, 9α-epoxymethano-15S-hydroxyprosta-5Z,13E-dienoic acid; TP agonist)>prostaglandin F 2 α (FP receptor agonist). Sulprostone (EP 1 /EP 3 -selective), fluprostenol (FP-selective) and cicaprost and iloprost (both IP-selective) had minimal effects. It is likely that DP, EP 2 /EP 4 and TP receptors are present on the vagal fibres of the ferret.