Background: Coronary artery microvascular dysfunction is prevalent in women with chest pain in the absence of obstructive coronary artery disease (CAD) and is manifested by attenuated coronary flow reserve (CFR). Markers of inflammation and endothelial cell activation have been found to be elevated in patients with chest pain but without CAD. The relationship between inflammation, endothelial activation, and CFR is not known. Methods: Ninety-four women with chest pain in the absence of obstructive angiographic CAD underwent catheterization-based assessment of CFR and measurement of levels of inflammatory markers (n = 78) and endothelial cell activation in the NHLBI WISE study. Results: Coronary flow reserve did not correlate with levels of C-reactive protein (high-sensitivity C-reactive protein) (rs = -0.07, P = .53), interleukin (IL)-6 (rs = -0.12, P = .31), IL-18 (r s = 0.14, P = .23), tumor necrosis factor α (rs = -0.09, P = .43), transforming growth factor β1 (rs = 0.02, P = .84), and soluble intracellular adhesion molecule-1 (rs = 0.04, P = .68). Median levels of markers of inflammation and endothelial cell activation did not differ between the 57 women with abnormal CFR (<2.5) and the 37 women with normal coronary microvascular function (high-sensitivity C-reactive protein 0.32 vs 0.25 mg/dL, P = .80; IL-6 2.89 vs 2.39 pg/mL, P = .63; IL-18 218 vs 227 pg/mL, P = .59; tumor necrosis factor α 2.7 vs 2.4 pg/mL, P = .43; transforming growth factor β1 9928 vs 12 436 pg/mL, P = .76; soluble intracellular adhesion molecule-1 286 vs 287 pg/mL, P = .95). Multivariable models demonstrated no evidence of associations between markers of inflammation and of endothelial cell activation and CFR. Conclusions: Coronary microvascular dysfunction is not associated with markers of inflammation and endothelial cell activation in women with chest pain in the absence of obstructive CAD. These results suggest that inflammation and endothelial cell activation may not play a pathophysiological role in coronary microvascular dysfunction. © 2005, Mosby, Inc. All rights reserved.