["Fractional exhaled nitric oxide (FENO) and exercise testing are widely used for the evaluation of pediatric asthma. The evidence relating to the effects of strenuous exercise on FENO in children is conflicting. Little information is available on the association between exercise and FENO in relation to allergic rhinoconjunctivitis (AR). We aimed to investigate the effects of AR on children's FENO in response to a standardized treadmill exercise test.", 'A total of 124 children with current asthma and 124 non-asthmatic children aged 8-16 years were studied. FENO was measured at baseline, at 1 and 30\u2009min after an exercise challenge test using the single breath technique with EcoMedics Exhalyzer. A structured parental interview, spirometry, serum allergen-specific IgE and skin prick tests were performed.', 'Baseline FENO was higher in both asthmatics and non-asthmatics with AR than without AR (both p\u2009<\u20090.001). The FENO time trend was dependent on AR (p\u2009=\u20090.039), irrespective of asthma (p\u2009=\u20090.876). In children with AR, FENO had declined at 1\u2009min by a mean of 6.1 ppb with a 95% confidence level of 5.1-7.5 ppb; at 30\u2009min, the reduction was 2.8 (2.5-3.3) ppb. In children without AR, at 1\u2009min the decline in FENO was 2.7 (2.1-3.5) ppb and by 30\u2009min post-exercise it was 1.6 (1.3-2.0) ppb.'] Does the effect of exercise on exhaled nitric oxide depend on allergic rhinoconjunctivitis in children?