Treatment guidelines suggest antipsychotic monotherapy in the treatment of psychosis. 20-40% of patients take combination therapy in clinical practice due to inadequate treatment response to monotherapy. First-generation antipsychotic monotherapy was ineffective in case of our patient who had severe psychotic symptoms. Switching to a second generation antipsychotic had partial therapeutic effect, the severe psychotic condition was persistent. For this reason the therapy was changed to olanzapine-clozapine combination. Due to this combination the patient's psychotic symptoms disappeared. He was able to maintain the relationship with psychiatrist. During this therapy we observed good compliance, no more drug abuse and no relapse.