Spikes of single pontine pause neurons (PNs) in the cat were recorded extracellularly and identified by observing cessation of tonic discharges before and during the fast phase of vestibular nystagmus. PNs were antidromically activated from the excitatory burst neuron area. Antidromic spikes were abolished or their peak latencies were prolonged during particular periods within a nystagmic cycle. The excitability change in PNs indicated by alteration of the antidromic responses occurred with two stages; i.e. a moderate decrease in excitability before the onset of the fast phase and an abrupt, intense decrease starting form the beginning of the fast phase.