We sought to determine plasma levels of platelet/endothelial cell adhesion molecule-1 (PECAM-1), P-selectin, and platelet-derived osteonectin, and prospectively compare these data with the discharge diagnosis in patients presenting with chest pain in a community hospital Emergency Department. Soluble antigens were measured by ELISA in 44 subjects including patients with acute myocardial infarction (AMI) (n = 13), chest pain of noncardiac origin (n = 17), and compared to those of age- and sex-matched healthy controls (n = 14). Elevated soluble PECAM-1 (64.5 +/- 18.3 ng/ml, p = 0.019), but not P-selectin (149.5 +/- 49.8 ng/ml, p = NS), nor osteonectin (549. 5 +/- 159.1 ng/ml, p = NS), occurred in the AMI group as compared to patients with noncardiac chest pain (46.2 +/- 7.5 ng/ml, 118.2 +/- 40.1 ng/ml, and 619.4 +/- 74.4 ng/ml, respectively). Increased plasma PECAM-1 may serve as a useful marker in the early detection of patients with AMI. Larger studies will be necessary to confirm the utility of soluble PECAM-1 in identifying AMI among patients presenting with chest pain.