The purpose of this study was to investigate the possible relationship between circulating intercellular adhesion molecule-1 (cICAM-1) plasma levels and Behçet's disease. Plasma levels of cICAM-1 were measured in 44 patients with Behçet's disease and in 30 healthy controls. cICAM-1 levels were higher in patients with Behçet's disease than in the controls (P=0.001). The difference was more marked between patients with active Behçet's disease and controls (P < 0.001). cICAM-1 levels were also higher in patients with active Behçet's disease than in those with inactive disease (P<0.001). cICAM-1 seems to be related to disease activity in Behçet's disease. It may be useful in assessing disease activity in Behçet's disease, as well as in monitoring response to treatment.