The aim of the study was to localize brain parts involved in executive functions in patients with schizophrenia by means of 99mTc-ECD single photon emission computed tomography (SPECT) with 3-dimensional automatic software. We examined 12 men with schizophrenia (mean age 29±3.9 years). Brain perfusion SPECT was performed at rest and during Wisconsin Card Sorting Test (WCST). Two types of quantitative SPECT analysis were applied; voxel-based and volume of interest (VOI)-based. With voxel-based approach, rest and activation SPECT were compared. VOI-based analysis allowed for correlation of regional cerebral blood flow (rCBF) in 20 VOIs with WCST scores. In voxel-based analysis, the patterns of rCBF decrease and increase after activation varied between patients, with combinations of different brain regions involved. In VOI-based approach, the only statistically significant difference between activation and rest was rCBF decrease in the left basal ganglia (p=0.028). The thalami and right temporal cortex correlated with the greatest number of WCST scores, followed by left occipital cortex and left cerebellum. In conclusion, our results suggest that patterns of WCST activation and deactivation vary between patients with schizophrenia. Among the network of involved brain structures, right temporal cortex and thalami appear to play the major role.