The WHO has undertaken an update of the 1998 WHO Cancer Pain Relief and Palliative Care in Children Guidelines, in extending the scope to persisting pain associated with other medical conditions. The new WHO Guidelines for Pharmacological Treatment of Persisting Pain in Children with Medical Illnesses, using the GRADE approach for evidence synthesis and grading of recommendations, are expected to help reduce the enormous treatment gap for pain in children. The WHO aims to update these guidelines within the next five years. Given the paucity of studies in the paediatric population with persisting pain, a meaningful revision of these guidelines will need the international scientific community to invest in research on the topics that were identified as evidence gaps during the development process For this reason, the WHO calls for a collaborative effort to cover the identified priority research areas and related systematic reviews of evidence. Copyright © 2011 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. The Cochrane Collaboration