As has been highlighted on World TB day, children with TB are a neglected population usually omitted from research in treatment and diagnostics. Accurate diagnosis of Mycobacterium tuberculosis in children has long been difficult and current diagnostic tools available fail to address the problems experienced in diagnosing TB in children. There is a desperate need for new rapid, accurate diagnostic tests for children. The development of new tools for children has been hampered by a lack of consensus on case definitions for research purposes. Children are usually excluded from studies into new technologies and when they are included, the lack of a clear reference standard has presented difficulties comparing paediatric diagnostic studies due to the different methodologies and case definitions used. Research into paediatric TB diagnostics is very limited and a consensus on a reference standard should promote further research and ensure that the maximum benefits can be gained from it. The National Institute of Health sponsored a meeting in June 2011 "Critical Issues in Paediatric Tuberculosis Diagnostics Research in HIV-Infected and Uninfected Children", bringing together a group of leading paediatric TB experts. The meeting addressed the lack of an agreed reference standard for diagnostics, and an expert consensus was reached on clinical case definitions for intra-thoracic TB diagnosis in children. Consensus was also reached on how to standardise methodological approaches for evaluation of new TB diagnostic tests in children. The published consensus statements clearly specify how to use these definitions to reliably classify a child for research purposes.