• With the discovery of the opiate peptides, several major avenues of research became apparent. These peptides produced a great deal of focused attention on their anatomy, biochemistry, and physiology. In this article, we present an overview of some of the main research issues and recent findings in the field of opiate peptides. The possible relationship of the opiate peptide neuronal systems to schizophrenia is discussed in light of attempts to alter schizophrenic symptoms with opiate antagonists, β-endorphin, and dialysis. It is hypothesized that if the opiate peptides are involved in schizophrenia, then their involvement with dopamine systems and/or with stress responses may be critical.