The participation of adhesion molecules in systemic vascular injuries of the generalized Shwartzman reaction was studied. The generalized Shwartzman reaction was induced in mice by two consecutive injections of lipopolysaccharide. Intercellular adhesion molecule-1 (ICAM-1) was expressed on vascular endothelial cells, renal tubular cells and alveolar wall in generalized Shwartzman reaction-induced mice. The preparative injection of lipopolysaccharides induced ICAM-1 expression in those cells, and the provocative injection of lipopolysaccharides for the generalized Shwartzman reaction augmented it further. The simultaneous administration of anti-gamma interferon antibody with the preparative injection of lipopolysaccharides completely inhibited ICAM-1 expression on vascular endothelial cells. The injection of recombinant gamma interferon in replacement of lipopolysaccharides resulted in ICAM-1 expression. The administration of anti-ICAM-1 antibody together with the provocative injection of lipopolysaccharides significantly blocked the apoptosis of vascular endothelial cells in generalized Shwartzman reaction-induced mice. It was suggested that ICAM-1 expression on vascular endothelial cells might be involved in systemic vascular injuries of the generalized Shwartzman reaction, and that it might be regulated by gamma interferon.