Synaptic vesicles (SVs) are small, electron-lucent vesicles that are clustered at presynaptic terminals. They store neurotransmitters and release them by calcium-triggered exocytosis. SVs are made locally at the terminals and are regenerated after exocytosis. In respect to their pivotal functions in neurotransmitter release, SVs should be equipped with two sets of functional components, proteins for nuerotransmitter uptake and for membrane trafficking. We have learned much about the molecular composition of SVs, but we are still on the way to achieve mechanistic descriptions of how SVs are functioning in neurotransmitter release. © 2009 Elsevier Ltd All rights reserved.