Glutamate receptors constitute a complex signalling system at most of the excitatory synapses in the brain. Of the known ionotropic glutamate receptors, kainate receptors are ubiquitous in the central nervous system, and a considerable amount of data indicates that this class of receptors is present at both sides of the synapse. Pre- and postsynaptic kainate receptors are able to regulate both transmission of information and excitability in a synapse-specific manner. Proteins interacting with kainate receptor subunits are being identified and functional studies have provided evidence of the existence of a dual signalling system. It has become clear that these receptors have a role in synaptic plasticity and that they might also have a fundamental role in epilepsy through the strategic control of network excitability. However, the role of kainate receptors in other brain pathologies remains obscure.