Studies have shown disparate results in relation to the role of plasma concentrations of inflammation markers such as fibrinogen, cytokines, and cell adhesion molecules in acute coronary syndromes. The differentiation of primary versus secondary alterations of these markers in response to acute coronary syndromes is not clear. The aim of this study was to investigate the effect of soluble cell adhesion molecules and some inflammatory markers on coronary plaque instability. The prospective study consisted of 15 patients with stable angina pectoris (SAP), 16 with unstable angina pectoris (UAP), and 16 who had undergone percutaneous transluminal coronary angioplasty (PTCA). Blood samples were obtained from the SAP group on admission, from the UAP group at the early stage of pain onset within 6h of pain, and again after 12h of pain. Samples from the PTCA group were collected before, 2, 14h after the procedure. Soluble vascular cell adhesion molecule-1 (VCAM-1), endothelial selectin, interleukin-1β (IL-1β) and interleukin-2 (IL-2), and C-reactive protein (CRP) were analyzed by enzyme-linked immunosorbent assay. CRP serum levels gradually increased although IL-2 gradually decreased in patients with UAP and PTCA. In addition, VCAM-1 levels were sharply decreased after the PTCA procedure. However, this value returned back to the preprocedure levels 14h after PTCA. Both CRP and IL-2 are directly involved in the triggering mechanisms of acute coronary events.