Serum levels of soluble interleukin-2 receptor (sIL-2R), intercellular adhesion molecule-1 (ICAM-1), endothelial leukocyte adhesion molecule (ELAM-1), and eosinophil cationic protein (ECP) were measured in 20 patients with atopic dermatitis before and after 4 days' treatment with prednisolone p.o. as well as in 16 healthy, nonatopic controls. Before steroid treatment, patients with atopic dermatitis demonstrated significantly higher serum levels of sIL-2R, ICAM-1, and ECP than healthy controls (P < 0.001), whereas ELAM-1 levels were not different between the groups. After 4 days of steroid treatment, clinical improvement was associated with a decrease of sIL-2R (P < 0.003), ICAM-1 (P < 0.004), and ECP serum levels (P < 0.003), but ELAM-1 levels remained unchanged. Both serum ECP and sIL-2R levels were significantly correlated with disease severity before as well as after steroid treatment. Changes of sIL-2R concentrations were strongly related to the changes of ECP levels. In addition, changes of serum sIL-2R and ECP levels in percentage were correlated with clinical improvement. These results indicate that the determination of sIL-2R and ECP serum levels may be useful in monitoring disease activity in atopic dermatitis in childhood, especially in treatment trials.