Functional and structural neuroimaging help us to compare the brains of schizophrenic patients and controls, moreover they let us observe the changes with treatment. Longitudinal studies comparing patients with typical and atypical antipsychotics have been useful in understanding the effects of these antipsychotic medications on brain function. In general, atypical antipsychotics are suggested to have greater normalizing effects on brain function than typicals, although the results are controversial. In particular, clozapine appears to act more selectively than typical antipsychotics on the prefrontal region, an area of special relevance in higher cognitive functions and schizophrenia. The study of anatomic and functional brain variables associated with clozapine response in schizophrenia may help to identify patients who are most likely to benefit from clozapine treatment. We investigated the effect of clozapine on regional cerebral blood flow and H-1 MRS findings and studied their relationship with treatment response. Clozapine increased frontal/basal ganglia perfusion ratio in treatment-responders. In addition, NAA/Cre ratio has increased and Cho/Cre has decreased in dorsolateral prefrontal cortex after 8 weeks of clozapine treatment. The results of the study will be discussed in the light of current literature. These findings can contribute to better understanding of mechanism of action of clozapine.