SUMMARY The actions of cyclopropane, halothane, and ether on sympathetic ganglionic transmission were studied by recording the compound action potential evoked in postganglionic nerves by single shock stimulation of the preganglionic pathways. The ganglia investigated were the superior cervical and inferior mesenteric in the rabbit, and the superior cervical and stellate ganglia in the cat. All three anaesthetics reduced the height of the postganglionic compound action potential. This effect is interpretable as partial ganglion block, but requires further study in view of the increased discharge rate measured in both pre- and postganglionic sympathetic nerves during associated studies with inhalation anaesthetics in rabbits.