Paired tight-seal whole-cell recordings were obtained from neighboring Purkinje cells in cerebellar slices. Under voltage clamp, spontaneous inhibitory postsynaptic currents resulted from the activity of GABAergic interneurons, stellate and basket cells. Up to 80% of inhibitory postsynaptic currents in paired recordings were in register. This correlation was not affected by antagonists of glutamate receptors, faded with distance, and was abolished by tetrodotoxin. Earlier work showed that voltage-gated Ca2+ entry into a Purkinje cell elicits a transient presynaptic inhibition of inhibitory postsynaptic currents. It is now shown that this inhibition is not restricted to the stimulated cell, but that it is transmitted to its neighbors. The results indicate that Purkinje cells exchange information by an unconventional mechanism involving retrograde control of inhibitory synapses.