The purpose of the study was to compare neuropsychological characteristics and structural and functional brain abnormalities in patients with schizophrenia and bipolar affective disorder. 23 patients who met DSM-IV criteria for schizophrenia and 13 patients in manic episode of bipolar affective disorder vere included in the study. After neuropsycological evaluation, brain MRI and SPECT studies were perfoı-ıned. In statisticall analysisi chi-.square and Mann-Whitney U tesis were applied. In terms of neuropsycological pe ıformance, the schizophrerric patients esere; srgnificantly worse tha ıı the manic patients, especially on measures of executive functions, memory and visual -spatial functions. On global assessment of MRI results, structural brain pathologies were detected in 56% of schlzophrenic and 70% of manic patients. When two patient groups compared, no significant differences emerged. SPECT analyse: revealed that, there were bilateral decrease of blood peıfusion more significant on the left hemisphere irr both schizophrenic and manic patients. Between patient groups no significant differences were detected.