The discovery of the endorphins has opened up a new dimension for research into the biological determinants of schizophrenic behaviour. However, it would be premature to advance an endorphin hypothesis on the pathogenesis of schizophrenic psychoses at this time. Technical difficulties have so far been an obstacle in the study of the human central endorphin metabolism. The therapeutic aspect of endorphin research shows some interesting features. Opiate (endorphin) antagonists certainly do not seem to be universal antipsychotics, but undoubtedly it is worthwhile to continue the search for subgroups that are susceptible to these compounds. The reverse of this strategy has also been applied: administration of endorphins to schizophrenic patients. Of the three compounds used in this context — fl-endorphin, a synthetic met-enkephalin derivative and DTyE — the latter is the most interesting. It is a naturally occurring fragment of y-endorphin which lacks morphinomimetic effects and has certain pharmalogical as well as clinical properties in common with the traditional neuroleptics. This compound may well open up entirely new perspectives for the treatment of schizophrenic psychoses.