Introduction: Studies with single photon emission computed tomography (SPECT) have revealed inconsistent changes of regional cerebral blood flow (rCBF) in schizophrenia. Some studies investigated the rCBF and its relationship with psychopathology, positive and negative symptoms in treated patients. However, there is a little information about the pattern of rCBF in recently untreated or never treated schizophrenic patients. The aim of this study was to evaluate the pattern of rCBF of the drug-naïve or drug free schizophrenic patients. Methods: Thirty-three patients with schizophrenia participated in the study. For each subject, the regional brain perfusion was evaluated with SPECT and the clinical state was assessed according to PANSS and CGI in a medication-free state. Also a group of 12 cases without any history of neurological or psychological disorder was enrolled as a control group for comparing of the SPECT data. Regional perfusion indices (RPI) were defined as mean count per pixel in each of 25 brain regions normalized to the mean count per pixel of the whole brain. The RPI patterns were compared in control and patient subjects. Results: In comparison with control subjects, the RPI of the anterior cingulate and inferior parts of the prefrontal and temporal cortices of the schizophrenic patients are significantly higher while the RPI of the occipital and parietal regions are unilaterally lower. Different schizophrenic patients showed hyperperfusion as well as normal or hypoperfusion in different regions of the brain cortex. However, hyperperfusion rather than hypoperfusion mainly is seen in the inferior prefrontal and temporal regions, while hypoperfusion patterns are more prominent in the cerebellar, occipital, parietal and dorsolateral prefrontal cortices. Conclusion: Different patterns of brain perfusion are seen in drug-free or drug-naïve patients with schizophrenia. Hyperperfusion in the frontal and temporal regions and hypoperfusion in the cerebellar, parietal and dorsolateral prefrontal cortices are the most predominant abnormal patterns in these cases.