This chapter represents a summary of the findings from the Yersinia enterocolitica strain 8081 whole genome sequence and the associated microarray analysis. Section 1 & 2 provide an introduction to the species and an overview of the general features of the genome. Section 3 identifies important regions within the genome which highlight important differences in gene function that separate the three pathogenic Yersinias. Section 4 describes genomic loci conferring important, species-specific, metabolic and virulence traits. Section 5 details extensive microarray data to provide an overview of species-specific core Y. enterocolitica gene functions and important insights into the intra-species differences between the high, low and non-pathogenic Y. enterocolitica biotypes.