The splanchnic-chromaffin cell synapse is the site at which stimulus-secretion coupling in the adrenal medulla is regulated. However, since the discovery that acetylcholine underlies chemical signaling at this synapse, attention has been disproportionately placed on postsynaptic chromaffin cell function. As a result, the determinants of Ca2+-sensing and exocytosis from splanchnic nerves remain poorly understood. This study shows, for the first time, that a ubiquitous Ca2+-binding protein, synaptotagmin-7 (Syt7) is expressed within the neurons that innervate the adrenal medulla. In synapses that lack Syt7, evoked excitatory postsynaptic currents (EPSCs) are smaller in amplitude and decay with more rapid kinetics than wild-type synapses stimulated in an identical manner. EPSCs in Syt7-deficient adrenal slices also fail to facilitate, which is ordinarily a robust property of these synapses. These data are the first to implicate a role for Syt7 in regulating short-term synaptic plasticity in the peripheral nervous system.