Fractional exhaled nitric oxide (FeNO) has been reported to be reduced in cystic fibrosis (CF) patients. However, data from young children are conflicting and it is not clear whether this is a primary feature of the disease or a secondary response. The present study compared FeNO between CF and healthy infants using a validated single-breath technique.A total of 23 healthy infants (11 females; mean age 40.1 weeks) and 18 infants with CF (nine females; 64.9 weeks) underwent tests of lung function and FeNO. Bronchoalveolar lavage (BAL) was collected from all CF infants 2-5 days after lung function testing.There was no significant difference in FeNO between the CF and healthy infants (geometric mean: 23.1 parts per billion (ppb) and 17.0 ppb, respectively). There was an inverse relationship between age and Fell in the CF patients, but not in the healthy group. Within the CF group, there was no association between FeNO and any marker of airway inflammation measured in the BAL.Exhaled nitric oxide is not reduced in cystic fibrosis infants, but does decrease with age. The current data indicate that FeNO is not a good marker of airway inflammation in cystic fibrosis.