Measurement of fractional exhaled nitric oxide in exhaled air is an exciting innovative technique that gives new insights in to the pathophysiology of lung disease and asthma in particular, with many potential clinical applications. Careful standardisation of measurement techniques will facilitate the use of this new measurement in paediatric respiratory medicine: this Task Force was set up for this purpose. Methodologies, for use in all age groups, are already available and there are abundant questions relating to interpretation and application of fractional exhaled nitric oxide waiting to be addressed. Noninvasiveness and instantaneous results potentially make it a suitable monitoring instrument for use in children. Exhaled nitric oxide measurement has definitely found its way into clinical research in paediatric respiratory medicine. Evidence for clinically-useful applications is accumulating, and the merits of this new technique must now be demonstrated in larger studies, using standardised methodology in an appropriate setting.