There is agreement among international nutrition organizations and healthcare accrediting organizations that nutrition screening is essential to identify patients needing further nutrition assessment to determine appropriate nutrition intervention. Numerous nutrition screening tools are used in hospitals, but many, if not most, have never been validated for the care setting, patient population, or outcome they strive to identify. Thus, it is unclear if they appropriately identify patients who truly need further nutrition assessment and, potentially, intervention. Several nutrition screening tools reported in the literature have been validated in a variety of care settings and patient populations and have been shown to achieve the desired outcome. These tools include the Malnutrition Universal Screening Tool, Nutritional Risk Screening 2002, Mini Nutritional Assessment, Short Nutritional Assessment Questionnaire, Malnutrition Screening Tool, and the Subjective Global Assessment. It is important for clinicians to understand how the tools were validated and for which population and care setting they were developed, and to determine if the tool might be appropriate for use in their institution.