Intercellular adhesion molecule-1 (ICAM-1) is a membrane-bound molecule primarily involved in cell-cell adhesive interactions of the immune system. It is a cytokine-induced glycoprotein involved in the recruitment of cells into tissues undergoing inflammatory responses. The levels of soluble ICAM-1 were measured in sera of patients with systemic lupus erythematosus (SLE) using sandwich enzyme-linked immunoassay. Serum levels (mean +/- SD) of soluble ICAM-1 (sICAM-1) were significantly higher in 24 patients with SLE than in 20 controls (372 +/- 42 ng/dL vs 231 +/- 29 ng/dL, P < 0.001). A statistically significant positive correlation was observed between sICAM-1 levels and SLE disease activity index (SLEDAI) score in SLE patients, and no correlation was found between sICAM-1 and CRP, SLEDAI and CRP, or SLEDAI and ESR in patient groups (P > 0.05). These findings suggest that sICAM-1 measurement may serve as an additional serologic marker of disease activity in patients with SLE.