Abstract: Three ypes of discharge pattern were recorded from the cardiac vagal efferent nerve of the rabbit immobilized with flaxedil.1.Rhy thmical discharges synchronized with efferent impluses in the phr-enic nerve.Two phases were distinguished in each discharging period:the first phase was roughly simultaneous with the phrenic eiferent flow,and the second one developed during the later period of the phrenic efferent discharges or just after the phrenic efferent discharges had ended;2.Constant discharges,appearing during the intermittence periods of the rhy-thmical discharges mentioned above in 1;3.Bursting discharges with much higher amplitude and freque ncy occurred occasionally.The phrenic efferent discharges were obviously depressed whenever the burst appeared. The cardiac vagal efferent dis-charges could be inhibited signifi-cantly by intravenous injection of urethan.