Previous studies have suggested that intercellular adhesion molecule–1 (ICAM–1; CD54) may be involved in the pathogenesis of asthma. In addition, a soluble form of intercellular adhesion molecule–1 (sICAM–1) has been detected in increased concentrations in the sera from adult patients with certain inflammatory, immune, or malignant diseases. To determine whether bronchial asthma exacerbation in children is associated with increased levels of serum sICAM–1 and to investigate the effect of the severity of exacerbation on these levels, the concentrations of sICAM–1 were measured in sera of 20 healthy control children and 45 asthmatic children (15 with mild, 15 with moderate, and 15 with severe asthma exacerbation) using an immunoenzymatic assay. Assessment of the severity of asthma exacerbation was based on clinical and physiological parameters. The mean (± SD) level of serum sICAM–1 for asthmatic children (390.0±108.3 ng/ml) was significantly higher than that for healthy (193.2±33.95 ng/ml; p = 0.000). We have also found a differential rise of serum sICAM–1 level which correlates well with the severity of asthma exacerbation. The elevated concentrations of serum sICAM–1 in acute bronchial asthma may reflect the extensive inflammatory response occurring in the airways during acute exacerbation of the disease with airway obstruction. The results of this study suggest that serum sICAM–1 is a promising serological marker of the severity of inflammation in bronchial asthma in children and it would not only facilitate staging of inflammation but also allow the monitoring of therapy and intervention.