Abstract Aims and Objectives To compare three risk assessment scales with respect to predictive validity Background In paediatrics there are several competing scales and at least ten published paediatric pressure ulcer risk assessment scales have been identified. However there are few studies exploring the validity of such scales, and none identified that compares paediatric risk assessment scales. Design Cross sectional study Methods Three risk assessment scales, Braden Q, Garvin and Glamorgan, were compared. The total scores and sub-scores were tested to determine if children with pressure ulcers were significantly different from those with no pressure ulcer. Logistic regression was conducted to determine if the probability of developing a pressure ulcer was a better predictor of development of pressure ulcer compared with the total score of each scale. Receiver operating characteristic curves were computed and the area under the curve used to compare the performance of the risk assessment scales. Results Data from 236 children were collected. 71 were from children in eleven hospitals who were asked to provide data on children with pressure ulcers (although seventeen did not have a pressure ulcer) of whom five were deep (grade 4). A sample of 165 were from one hospital, of which seven had a pressure ulcer, none grade four. The Glamorgan risk assessment scale had a higher predictive ability than either the Braden Q or Garvin. The mobility sub-score of each of the risk assessment scales was the most predictive in each case. Conclusions The Glamorgan scale is the most valid of the three paediatric risk assessment scales studied in this population. Mobility alone may be as effective as employing the more complex risk assessment scale. Relevance to clinical practice If a paediatric risk assessment scale is employed to predict risk, then unless it is valid, it may identify children who are not at risk and waste resources, or fail to identify children at risk possibly resulting in adverse health outcomes.