Rationale: We aimed to assess the methodological quality of studies investigating the validity of nutrition screening tools for detecting the risk of undernutrition in hospitalized children, as a first step to formulate an evidence-based decision on the best screening tool. Methods: A systematic review of literature was carried out to identify articles on paediatric nutritional screening tools for hospitalized children in developed countries. MEDLINE, EMBASE and Cochrane Central databases were searched until 1/12/12. Methodological quality of the studies was assessed independently by two reviewers using the Cochrane version of the QUADAS tool. Results: 13 articles met all inclusion criteria. Five were excluded (no reference standard: n = 4, no separate paediatric data: n = 1). 4 studies (310 children) on the Screening Tool for the Assessment of Malnutrition in Paediatrics (STAMP), 2 (579 children) on the Paediatric Yorkhill Malnutrition Score (PYMS), the Screening Tool Risk on Nutritional status and Growth (STRONGkids) (467 children) and the Pediatric Nutritional Risk Score (PNRS) (366 children) were included (some studies tested more than one screening tool). 2 studies (STAMP: n = 1, PNRS: n = 1) focused on children with specific diseases, others reported on a mixed population. Overall, the main concerns were a high risk of bias in the patient selection (PYMS: n = 2, STAMP: n = 1) and the appropriateness of reference standard: a full dietetic nutritional risk assessment (PYMS: n = 2, STAMP: n = 3), weight loss (PNRS: n = 2, STRONGkids:n = 1) or the need for a nutritional intervention (STAMP: n = 1, STRONGkids:n = 1). Conclusion: The main quality concerns of the available studies on paediatric nutrition screening tools are in the choice of the reference standards. We suggest to use the need of a nutritional intervention as a reference standard, or to report on inter-rater variability when dietetic assessment is used.