Aim. The aim of the study was a comparative analysis of the polymorphism in TH01 locus - tetranucleotide microsatellite region located in the first intron of the tyrosine hydroxylase gene (TH) between a group of Polish patients suffering for schizophrenia and their regionally matched healthy subjects. Method. One hundred patients affected by paranoid schizophrenia and healthy individuals with negative family history of psychiatric disorders as control, were investigated. Genomic DNA was isolated from peripheral blood, amplification of TH01 locus was carried out using the following sequences of primers: 5'-GTG GGC TGA AAA GCT CCCGAT TAT-3', 5'-ATT CAA AGG GTA TCT GGG CTC TGG-3', PCR products were detected on the ABI Prism 377 sequencer. Distributions of alleles, genotypes and homo-heterozygosity of the patients were compared with those of the matching controls using the RXC program created by G. Carmody. Relative Risk (RR) of the disease was calculated according to the formula given by Dyer & Werrens. Results. The conducted analysis showed the existence of statistically significant differences in the distribution of alleles, as well as genotypes between the schizophrenics and the control population. We revealed that 7 allele is present statistically significantly more often in the group of patients and its presence increases the risk of schizophrenia almost twofold (RR=1.89). Whereas the presence of 9.3 allele reduces the risk of the disease (RR=0.72), in the homozygote form 9.3-9.3 even over three times (RR=0.32). Conclusion. The revealed differences in the susceptibility to schizophrenia depending on polymorphic allele variants in repetitive TCAT sequence in TH01 locus may be associated with the function of a regulatory element in the process of TH gene transcription. Our findings need further investigation in a larger sample of patients.