Enterobacteria are gramnegative, facultative anaerobic bacteria that are rod-shaped. They occur in the natural environment, many are part of the human intestinal microflora (intestinal microbiome). According to the current classification, they belong to the order Enterobacterales, which includes 7 families, 66 genera and many species. Bacteria of the genera Escherichia, Enterobacter, Salmonella, Shigella, Klebsiella, Morganella, Proteus, Providencia, Serratia, Pantoea, Yersinia, Cronobacer, Citrobacter, Plesiomonas, Hafnia, are important in human medicine. The content of the lecture is the classification and basic properties of enterobacteria, pathogenicity, clinical syndromes, laboratory diagnostics, therapy and prevention are described for the most important enterobacteria.