summary  A 22-year-old man, suffering from a paranoid psychotic relapse due to a chronic schizophrenia, was admitted to our psychiatric hospital. Because of aggression secondary to his psychosis he had to be secluded for almost one year. Zuclopentixol, quetiapine and clozapine had no clinical effects, neither did the augmentation of clozapine result in an increase in plasma levels. We decided to augment the clozapine treatment with fluvoxamine. This resulted in an approximately 2,5 fold rise in the clozapine serum concentration and a remission of the psychosis, and the patient was discharged.