It was postulated that chronic blockade of the opioid system in neuroleptic-stabilized schizophrenic patients would have a beneficial behavioral effect. Eleven neuroleptic-stabilized psychotic inpatients received augmentation with nalmefene for an average of 36.7 days in a double-blind placebo-controlled study. The patients exhibited significant reductions in Bunney-Hamburg psychosis ratings and the Brief Psychiatric Rating Scale thinking disturbance subscale during the augmentation period. This study presents preliminary data supporting the hypothesis that chronic augmentation of neuroleptic-stabilized schizophrenic patients with opiate antagonists is beneficial.