The dicarboxylic amino acids, glutamate and aspartate, are excitatory neurotransmitters in many brain regions. Recent animal experiments with analogues of dicarboxylic amino acids that block their excitatory actions, suggest that such selective antagonists could have important therapeutic uses in neurology and psychiatry. The strongest evidence concerns epilepsy and disorders of the motor system. However, there are theoretical and experimental grounds for studying therapeutic applications in cerebral ischaemia and in chronic degenerative disorders. This review summarizes the experimental background, and proposes some key future studies.