Hypoxia promotes adherence of leukocytes to endothelial cells by inducing expression of adhesion molecules like intercellular adhesion molecule 1 (ICAM-1). Increased serum levels of circulating ICAM-1 (cICAM-1) have been reported in adults with sleep apnea and associated hypoxemia. This investigation assessed the hypothesis that the overnight change of cICAM-1 levels in children with snoring is correlated with the severity of obstructive sleep-disordered breathing. Evening and morning serum levels of cICAM-1 were measured in children with snoring referred for polysomnography. Twenty-five children with an apnea–hypopnea index greater than or equal to 5 episodes/h (5.5 ± 1.8 years), 30 subjects with an index less than 5 and greater than 1 (6.3 ± 2 years), and 19 children with an index less than or equal to 1 (7.1 ± 3 years) were recruited. Overnight change in cICAM-1 (log-transformed ratio of morning-to-evening levels) was similar in subjects with an apnea–hypopnea index greater than or equal to 5 episodes/h compared to those with an index less than 5 and greater than 1 or to children with an index less than or equal to 1 (−0.001 ± 0.08 vs −0.03 ± 0.09 vs −0.06 ± 0.1; p > 0.05). When multiple regression analysis was applied, apnea–hypopnea index, respiratory arousal index, and oxygen saturation of hemoglobin nadir were not significant predictors of overnight change in cICAM-1 levels. Thus, in children with snoring, overnight change in cICAM-1 levels is not related to severity of obstructive sleep-disordered breathing.