Following the gradual recognition of the importance of intracellular calcium stores for somatodendritic signaling in the mammalian brain, recent reports have also indicated a significant role of presynaptic calcium stores. Ryanodine-sensitive stores generate local, random calcium signals that shape spontaneous transmitter release. They amplify spike-driven calcium signals in presynaptic terminals, and consequently enhance the efficacy of transmitter release. They appear to be recruited by an association with certain types of calcium-permeant ion channels, and they induce specific forms of synaptic plasticity. Recent research also indicates a role of inositoltrisphosphate-sensitive presynaptic calcium stores in synaptic plasticity.