Intercellular adhesion molecule 1 (ICAM-1) plays an important role in inflammatory diseases. We investigated levels of circulating soluble ICAM-1 in patients with miliary tuberculosis (n = 8) and pulmonary tuberculosis (n = 49). We also attempted to compare ICAM-1 levels among pulmonary tuberculosis patients according to chest X ray classification of the Japanese Society for Tuberculosis. Significantly increased levels of circulating ICAM-1 were found in patients with miliary tuberculosis and extensive (extent 3) pulmonary tuberculosis (n = 9) compared to those of controls (n = 48), but not in patients with extent 1 (n = 24) or extent 2 pulmonary tuberculosis (n = 16). Immunohistochemical examination of the tuberculous lung tissues from the patients showed intensive cellular ICAM-1 on epithelioid cells and giant cells as well as on vascular endothelial cells. These results suggest that ICAM-1 is an important adhesion molecule in tuberculosis.