• The β-lipotrophin fragment des-tyrosine-γ-endorphin (DTγE) has been reported to have antipsychotic properties. We administered the compound without other psychoactive drugs to a subpopulation of schizophrenic subjects. Male patients with chronic psychotic illness and previous long-term neuroleptic therapy were given DTγE at a similar dose and duration of treatment that have been reported to be effective. No improvement in psychotic symptoms occurred; plasma prolactin level, a parameter characteristically altered by neuroleptic treatment, did not change. The beneficial effects of DTγE in schizophrenia may be specific to a diagnostic category, may be dependent on past pharmacologic treatment, or may occur only in combination with other drugs.