Exhaled nitric oxide (eNO) is a highly reactive biological mediator that has recently been associated with chronic tonsillar disease in adults, but there are no published data concerning eNO levels in their pediatric counterparts. The aim of this study is to measure mean eNO levels in children with chronic adenotonsillitis or adenotonsillar hypertrophy, and assess the effects of potential confounding factors. Children aged 3-17 years were divided into three groups (chronic adenotonsillitis, adenotonsillar hypertrophy and controls). Their eNO levels were measured in accordance with the international guidelines, and their other clinical and anamnestic characteristics were recorded. The mean eNO level in the children with chronic adenotonsillitis was slightly higher than that in the other groups, but there was no statistically significant between-group difference. Age (p=0.009), allergy (p=0.05) and body mass index (p=0.03), but not the mean grade of adenoidal or tonsil hypertrophy, were all statistically related to mean eNO levels. These preliminary results indicate the lack of an increase in mean eNO levels in children with chronic adenotonsillar disease, with no substantial difference between children with chronic adenotonsillitis and those with adenotonsillar hypertrophy.