Hair cells, like retinal photoreceptors release their transmitter continuously, modulating the rate of release as stimulus intensity changes. Both cell types have a presynaptic specialization, the synaptic ribbon, that is thought to accumulate or promote the release of vesicles. What are the mechanisms that allow continuous and rapid release at the hair cell synapse? Capacitance measurements have shown that hair cells can sustain high rates of membrane fusion, possibly corresponding to the release of hundreds of vesicles per ribbon per second (Moser & Beutner, 2000). We investigated the inner hair cell synapse in the postnatal rat cochlea by recording excitatory postsynaptic currents from afferent terminals contacting the inner hair cell. We propose from our data that the ribbon synapse operates by multivesicular release. I shall compare the quantitative analysis of capacitance measurements of vesicular fusion in hair cells and the analysis of postsynaptic currents at the IHC afferent synapse. We find both methods lead to similar results. I shall also discuss the comparison of anatomical data of the postnatal and the adult ribbon synapse. How much can we learn about the transmitter release mechanism in the adult cochlea from recordings in the immature system?