Background: The National Kidney Foundation-Dialysis Outcomes Quality Initiative (KDOQI) guidelines and the Renal Association recommend the use of either Kt/V or urea reduction ratio (URR) to measure haemodialysis adequacy. Objectives: To determine the methods used to measure paediatric haemodialysis adequacy and to assess consistency between calculations of single pool Kt/V (spKt/V) and URR. Design: A service evaluation was conducted to establish current practices in measuring dialysis adequacy. A prospective longitudinal study was conducted to compare spKt/V and URR. Participants: Thirty-two children were recruited consisting of 13 males and 19 females in five paediatric dialysis centres. Results: Inconsistencies were reported of the method of post-urea sampling with 4 of the 10 centres using the KDOQI recommended sampling method. Five dialysis centres reported using URR and five reported using spKt/V. There were substantial differences between the two measures. Using URR suggested that up to 44% of children did not receive adequate dialysis, whereas measurement by spKt/V suggested no more than 6% of the same dialysis sessions were not adequate. Conclusion: One standard measure should be used to assess dialysis adequacy in paediatric centres in England. KDOQI guidelines were not consistently followed in obtaining a post-urea blood sample and this procedure should be standardised. © 2014 European Dialysis and Transplant Nurses Association/European Renal Care Association.