Considerable information is available regarding the role of ionotropic glutamate receptors in the generation of interictal spikes. Progress in the study of metabotropic glutamate receptors (mGluRs) makes clear that activation of these receptors can contribute greatly to seizure discharges and epileptogenesis. The effects of activation of the different mGluR subgroups on neuronal hypersynchrony and the initiation and propagation of seizure discharges in hippocampal slices are discussed herein. To help one understand the mechanisms that underlie these effects, information regarding the action of mGluRs on cellular and synaptic properties is summarized. The data bring to the forefront the critical role of mGluRs in epilepsy and emphasize the anticonvulsant effects of group II and III mGluR activation as opposed to the convulsant action of group 1, which elicits seizure discharges and epileptogenesis in experimental models.