Background: Increased endothelial cell activation and vascular inflammation have been shown in patients with syndrome X. The aim of the present study was to elucidate early inflammatory markers related to coronary flow reserve (CFR) in subjects with syndrome X using transthoracic Doppler echocardiography (TTE). Methods and Results: A total of 135 individuals (mean age: 56짹11 years, M:F ratio =56:79) with angina or angina-like chest pain and a normal coronary angiogram were enrolled. CFR, using TTE and adenosine or dipyridamole, was measured within 2 weeks after coronary angiogram. The early inflammatory markers related to CFR; soluble vascular adhesion molecule-1 (sVCAM-1), interleukin-6 (IL-6), Monocyte chemoattractant protein-1 (MCP-1), and Lipoprotein associated phospholipase A2 (Lp-PLA2) were analyzed. There was an inverse correlation between sVCAM-1 and CFR (r= –0.225, p=0.014). In the 2 groups divided by a CFR of 2.0, sVCAM-1 was significantly higher in the CFR <2.0 group than in the CFR ���2.0 group (756짹323 pg/ml vs 628짹145 pg/ml, p= 0.007). In multivariate analysis, sVCAM-1 was an independent factors related to a CFR <2.0 (OR= 1.003, 95% CI= 1.001–1.006, p= 0.018) (Table). The cut-off value of sVCAM-1 509 pg/ml showed a sensitivity 83.3% and a specificity 82.0% for predicting CFR < 2.0 (Fig). Conclusions: sVCAM-1 is a sensitive marker for predicting syndrome X in subjects with chest pain and a normal coronary angiogram.