Yersinia enterocolitica is a human pathogen that causes gastroenteric infections. Various environmental signals control the expression of the virulence factors in pathogenic Y. enterocolitica strains. OmpR, a global transcriptional regulator controls the expression of a wide spectrum of genes, some of which are required for virulence. In this study, we amplified, cloned and sequenced a Y. enterocolitica Ye9 ompR gene. Deduced amino acid sequence has been shown to have 98% homology to the Y. enterocolitica O:8, Y. pestis, S. typhi and S. enterica serovar Typhimurium OmpR proteins. Additional cell culture experiments was performed to investigate whether OmpR takes part in the virulence of Y. enterocolitica. We found that the Y. enterocolitica ompR mutant was unable to invade HeLa cells. In conclusion, we have shown that OmpR is a very highly conserved protein among enteric bacterial pathogens which plays an important role in the Y. enterocolitica virulence.