The low levels of endogenous brain-derived neurotrophic factor (BDNF) in the mature nervous system have hindered attempts to determine the subcellular localization of this peptide. Through use of confocal and immunogold electron microscopy, Dieni et al. now show that in the adult mouse hippocampus, BDNF and its pro-peptide are located in presynaptic dense core vesicles but are absent in postsynaptic compartments. According to the authors, these findings challenge the dendritic release–retrograde signalling model of BDNF action in the CNS.