Natural killer (NK) cells are traditionally considered in the context of tumour surveillance and viral defence but their role in bacterial infections, particularly those caused by enteric pathogens, is less clear. C57BL/6 mice were orally gavaged with Citrobacter rodentium, a murine pathogen related to human diarrheagenic Escherichia coli. We used polyclonal anti-asialo GM1 Ab to actively deplete NK cells in vivo. Bioluminescent imaging and direct counts were used to follow infection. Flow cytometry and immunofluorescence microscopy were used to analyse immune responses. During C. rodentium infection NK cells were recruited to mucosal tissues where they expressed a diversity of immune-modulatory factors. Depletion of NK cells led to higher bacterial loads but less severe colonic inflammation; associated with reduced immune cell recruitment and lower cytokine levels. NK cell depleted mice also developed disseminated systemic infection when compared to control infected mice. NK cells were also cytotoxic to C. rodentium in vitro.