In this study, the existence of the Lr10 gene, which has an important place among the leaf rust disease genes, was investigated by using the SSR (Simple Sequence Repeats-Microsatelite) method in frequently used F1 hybrid genomes bread wheat that bred from Thatcher lines of CIMMYT Mexico. In order to reproduce the trial plant material, to perform cross-genotypes and to make field observations of leaf rust disease, 13 F1 lines, 22 bread ( Triticum aestivum L.) wheat varieties and 2 Thatcher lines (Lr10, Tc susceptible) a study was conducted at the experiment fields of Bursa Uludag University Faculty of Agriculture, Agricultural Application and Research Center between 2013-2017. genotypes were subjected to DNA analysis using the SSR (microsatite) method in the Seed Laboratory of the Field Crops Department of the Bursa Uludag University Faculty of Agriculture. The analysis results indicated the existence of the Lr10 gene in Karatopak, Kasifbey and Gun-91 varieties. In this study; The SSR technique was found to be useful for determining leaf rust resistance genes in bread wheat, and it was also concluded that the Thatcher (close isogenic) lines in the study had a narrow genetic structure, so it was considered a good marker genome to determine the screened resistance genes. It has been concluded that the use of molecular markers in determining genotypes containing resistance genes in breeding programs will be effective in the future.