E-selectin endothelial leucocyte adhesion molecule-1 is expressed on endothelial cells in distinct inflammatory skin diseases. E-selectin mediates the adhesion between activated endothelium and different inflammatory cells. To evaluate soluble E-selectin as a marker of disease activity in patients with atopic dermatitis and psoriasis, the concentration of soluble E-selectin, determined by ELISA, was studied in sera of patients before and after treatment and compared with normal non-atopic controls. The disease severity was established using clinical scoring systems. Levels of soluble E-selectin were significantly elevated in sera of patients with atopic dermatitis and psoriasis (as compared with controls). Clinical improvement, after treatment, in patients with atopic dermatitis, but not in psoriasis, was associated with a significant decrease in serum levels of soluble E-selectin. There was a significant correlation of soluble E-selectin and disease activity in patients with atopic dermatitis. These data indicate that soluble E-selectin is another parameter to evaluate the inflammatory response in atopic dermatitis and psoriasis. Determination of soluble E-selectin may be a useful measure of disease activity in atopic dermatitis.