To characterize the role of circulating intercellular adhesion molecules (ICAM-1) and E-selectin in patients with acute coronary syndrome, serum levels of ICAM-1 and E-selectin were measured by enzyme-linked immunosorbent assay (ELISA). Group 1 comprised 17 patients with acute myocardial infarction; group 2 included 17 patients with unstable angina; and group 3 included 19 control subjects. These 53 patients all had prolonged chest pain within 24 h and all underwent coronary angiography. Group 1 and 2 patients had significant coronary artery disease, while group 3 had normal coronary arteries. Blood samples were collected at the emergency department before antiplatelet agents were given. Serum levels of 1CAM-1 were higher in group 1 and 2 (383 +/- 27 and 337 +/- 11 ng/mL, respectively) as compared with group 3 (282 +/- 18 ng/mL) (group 1 vs 3, p<0.01; group 2 vs 3, p<0.05). The serum levels of ICAM-1 were not significantly different between group 1 and 2. Serum levels of E-selectin in group 1, 2, and 3 were 58 +/- 8, 51 +/- 4, and 58 +/- 5 ng/mL, respectively. The serum levels of E-selectin showed no significant difference among the three groups. In conclusion, serum levels of ICAM-1 were elevated in patients with acute coronary syndrome within 24 h, while the E-selectin levels did not change significantly. This finding suggests that adhesion molecule may play an important role in the postrolling process of leukocyte-endothelial cell interaction in acute coronary syndrome.