The authors present a basic review on clozapine (Leponex, Clozaril) which is one of the atypical antipsychotic drugs. It is a derivative of dibenzodiazepine, which contrary to classical neuroleptic drugs, does not exert a marked effect on the extrapyramidal system and its long-term use is not associated with the risk of development of irreversible tardive dyskinesia or dystonia. It is effective also in patients who are resistant to treatment with other neuroleptics and it has a more favourable effect on the negative symptoms of schizophrenia than classical neuroleptics. Its disadvantage is the increased risk of granulocytopenia and agranulocytosis (2%) and therefore its use is justified only in patients where there is evidence that they are resistant to other treatment. The mentioned risk can be controlled effectively by regular checks of the haemogram in patients taking clozapine, along with recording in the central data bank which has a consulting and control function and guaranteeing the method of correct administration of this drug and early therapeutic provisions in case of granulocytopenia. Despite the cost of treatment and checks of the haemogram, clozapine reduces the sum total of expenditure associated with the treatment of chronic schizophrenia by reducing the number of re-admissions to hospital, by shortening the period of hospitalization and by cutting indirect costs, which are influenced by a greater sociability of the patient and a greater probability of successful comprehensive therapeutic procedures.