Introduction/Background The study included 50 patients diagnosed with endometrial cancer (EC) stage I-II. The age of these patients, on average, was 49.1 ± 12.1 years and ranged from 54 to 86 years. Methodology The tumor DNA was extracted from mapped formalin-fixed, paraffin-embedded tissue sections to provide tumor samples for the assays (figure 1). The methylation status of the MLH1 gene was determined using the Methylation Specific Polymerase Chain Reaction (MS-PCR) method and specific primers for both unmethylated and methylated fragments. Results The frequency of MLH1 promoter methylation was 20.0% and was determined in 10 patients. The frequency of tumors with MLH1 promoter methylation increases during menopause, reaching 30.0% at the age of 50–59 years and 50, 0% of cases at 60–69 years and decreases in the age periods 70–79 years, reaching 20.0%.The analysis of the obtained results showed that in patients with EC, the presence of MLH1 epimutation was significantly higher in stage I of the disease. Abstract 2022-RA-807-ESGO Figure 1 Methylation chain-specific polymerization reation workflow Abstract 2022-RA-807-ESGO Table 1 MLH1 dependence on stage of the disease in patients with endometrial cancer in stages III The presence of MLH1 epimutation was observed in 22.0% of patients with stage I EC and only in 2 stage II patients. The results of the analysis of overall survival in patients, according to the presence of MLH1 epimutation, showed that 71% of women with MLH1 epimutation and 92.5% without MLH1 epimutation survived at 3 years.Conclusion MLH1 promoter methylation analysis would play a valuable role as a clinical biomarker.