Background: Gram-negative Salmonella bacilli are one of the most common bacterial causes of gastrointestinal infections. Well-selected and targeted microbiological diagnostics enable the detection and identification of the etiological agent of infection, however, standardized, routine and recommended methods do not always allow for the identification of the biological agent in an unambiguous manner. Next-generation sequencing has become an ideal tool for identifying microorganisms and tracking infection transmission in outbreaks for epidemiological purposes. Objective: The aim of the study was to assess the genomic relatedness of Salmonella Enteritidis strains using whole genome sequencing in the foodborne outbreak in August-September 2023 in the Silesian Voivodeship. Material and methods: The research material consisted of 11 strains of S. Enteritidis for which whole genome sequencing was performed using Illumina technology and the relationship between serotypes was assessed using bioinformatics tools. Results: The genomes of all S. Enteritidis isolates were assigned to HC2_53128, which may indicate a very close relationship between the strains. Conclusions: Whole genome sequencing enabled the assessment of the genomic relatedness of S. Enteritidis strains in the foodborne outbreak in August-September 2023 in the Silesian Voivodeship.