Evoked potentials (EP) are an important research instrument in psychopharmacology. They allow to investigate central nervous processes in a time range of milliseconds. Furthermore, they are useful as a link between the basal biochemical or neuroendocrinological and the psychological levels of description. The literature concerning the relationship between EP and the therapeutically important classes of psychoactive drugs (stimulants, neuroleptics, antidepressants, minor tranquilizers/sedatives, lithium salts, carbamazepine) was reviewed. The following two questions were treated separately: 1. What are the effects of psychoactive drugs on EP in healthy subjects and in patients? 2. Are EP suitable as predictors of the clinical response to psychopharmacological treatment? It was found that most effects of psychoactive drugs on the EP are not specific for one class of agents. Furthermore these effects depend on factors concerning the subject (e.g. age, gender, diagnosis, symptomatology, personality, initial value of the EP-variable), the treatment (e.g. dosage, duration), or the context and procedure of the EP recording. Therefore, the importance of evoked potentials for the classification of new psychoactive drugs has been limited until now. However, the EP research has stimulated the development of mostly psychological concepts about the way of action of some psychoactive drugs. The use EP as predictors of the response to psychopharmacological treatment seems to be promising. There are consistent findings concerning the prediction of the clinical response to stimulants and lithium salts.