Schizophrenia is a serious chronic psychiatric disease with the least favorable prognosis. Its psychopathological mechanisms are not fully understood. There are no standard neuroimaging diagnostic methods that reveal specific brain alterations in schizophrenic patients. Standard imaging techniques are supplemented by computer analysis that enables the comparison of a distinct brain structure volumes: gray matter (GM), white matter and cerebrospinal fluid. The existing results are heterogeneous and show alterations in many GM regions. The aim of the research: The aim of this research was to establish brain volumetric alterations in schizophrenic patients according to the number of psychotic episodes, clinical condition, duration of the disease, and the age of onset of the disease. Study design: Cross-sectional study. Subjects and methods: A control group consisting of 50 healthy volunteers was included in the study, as well as a test group containing 100 schizophrenic patients. Demographic clinical data were collected and statistical analysis for each subject was performed. Intensity of clinical symptoms was established by PANSS test. Brain magnetic resonance was performed using a 1.5 Tesla strength scanner. Voxel based morphometry was performed with programme modules CAT12 and SPM12, while the results images were obtained by xjView programme. Results: The study results showed the reduction of total and relative GM volume in schizophrenic patients. Besides the reduction of total and relative GM volume, several specific regions of reduced GM were revealed. They were found in: prefrontal, temporal, parietal and occipital cortex, limbic structures, basal ganglia and cerebellum. The number of psychotic episodes and the age of onset of the disease exert the influence on the total and relative loss of GM. The severity and duration of disease do not have the same overall effect, but do cause GM reduction in the aforementioned regions. The longer the disease, the alterations become more numerous and severe, regardless of patient’s age. The higher number of psychotic episodes is linked to a higher number of altered regions indicating the GM reduction. However, we were unable to establish the correlation between altered regional distribution and the number of psychotic episodes. The early onset of the disease, prior to brain maturation, results in heavier GM reduction than in patients with later onset of the disease, i.e. after the brain maturation had been completed. Severity of symptoms had no significant impact on the GM volume reduction, except in the early onset of the disease. Conclusion: The identification of the reduction in cerebral GM, as well as the identification of altered GM regions, helped us gain a better insight into the volumetric brain alterations in schizophrenic patients, depending on the clinical course of the disease.