Neurotransmitter release from transmitter storage vesicles is a regulated signalling event that has properties in common with other secretory systems. Biochemical characterization of mammalian synaptic vesicle proteins has recently converged with studies of protein traffic in non-neuronal cells and the genetic dissection of the yeast secretory pathway to give us a considerable amount of new data. Many new synaptic vesicle proteins have been characterized together with plasma membrane proteins with which they interact, and it appears that many of the participating components may be part of a general machinery for secretion, The new results significantly improve our understanding of the molecular mechanisms governing transmitter release. This review discusses the recent progress in terms of synaptic vesicle components and the proposed mechanisms for exocytosis.