Despite clozapine's unique effectiveness in patients with schizophrenia, a number of adverse effects have been recognised including abnormalities in lipid and glucose metabolisms. A high clozapine level in red blood cells (RBCs) and disturbed anti-oxidant enzyme activities in blood from schizophrenic patients prompted us to investigate lipid status and anti-oxidant enzyme defence in the blood of chronic schizophrenic patients on long-term clozapine therapy.