The hypothesis that chronic neuroleptic treatment may induce relapse in some schizophrenic patients has received considerable attention. This effect, usually called supersensitivity psychosis, has been attributed to neuroleptic-induced changes in mesolimbic or mesocortical dopaminergic receptors. However, research has not established that neuroleptics cause the proposed effect, and considerations of mechanism have not been separated from those of causation. The focus of research in this area should be the establishment or refutation of a causal relationship between chronic neuroleptic use and psychotic relapse.