Listeria monocytogenes is ubiquitous in the environment and in food processing plants. Consequently, foods are frequently contaminated. However, the occurrence rate of listeriosis is only about five cases per million people per year. Listeriosis primarily strikes immunocompromised individuals, pregnant women and the elderly with a fatality rate of 20-25%. The FDA is in the process of finishing a risk assessment that is being conducted as an initial step in reviewing its approach to maximizing the public protection from foodborne L. monocytogenes. The risk assessment evaluated the presence and quantitative levels of L. monocytogenes in 21 groups of ready-to-eat foods. The potential growth of L. monocytogenes between retail point-of-sale, where contamination data originated, and consumption was modelled. The frequency and amount of consumption of these foods completed the data for the exposure assessment. For the hazard characterization or dose response part of the risk assessment, data from animal studies, virulence assays and epidemiological investigations were used to estimate the likelihood of illness for different human groups from consuming different numbers of L. monocytogenes. This risk assessment is a virtual review of current scientific knowledge. Quantitative modelling provides greater insight than a qualitative review and also indicates the uncertainty about our knowledge. The risk assessment does not attempt to define an acceptable or tolerable level of L. monocytogenes consumption or propose changes in regulations. These decisions are the responsibility of risk managers who consider additional factors such as food preferences, technical feasibility and societal values when evaluating regulatory policies.