This study was carried out to evaluate the loss of heterozygosity (LOH) in the 8q12-q24.1 chromosomal region, containing RAD54B gene in breast cancer. Polymorphic markers D8S539 and D8S543 were used. For alleles frequency estimation 100 primary breast cancers were tested. DNA was isolated from paraffin-embedded tissues and their matched blood samples. Polymerase chain reaction amplified products of normal and tumor DNA pairs were compared in ABI PRISM 377 DNA sequencer. In analyzed cases LOH was found in 1% and 2% of informative cases for microsatellite markers D8S539 and D8S543, respectively. This date indicate, that LOH isn't predictive for breast cancer.