Background: Previous studies have shown an association between C-reactive protein (CRP) and arterial stiffness in most cardiovascular diseases. Increased CRP levels and arterial stiffness have been considered independent predictors of cardiovascular mortality in cardiovascular disease and even in the general population. Objective: The aim of this study was to investigate the relationship between CRP, a marker of systemic inflammation and aortic stiffness in patients with idiopathic dilated cardiomyopathy (DCMP). Methods: Serum CRP levels and aortic stiffness parameters were measured in DCMP patients (n =37) and age- and gender-matched control subjects (n = 30). High-sensitivity CRP levels were determined by an immunonephelometry assay. Aortic strain (AS) and aortic distensibility (AD) were calculated from the aortic diameters measured using M-mode echocardiography and blood pressure obtained by sphygmomanometry. Results: Serum levels of CRP in DCMP patients were higher than in the control subjects (5.47 +/- 2.06 mg/L and 2.35 +/- 0.47 mg/L, P < 0.001, respectively). AS and AD were significantly decreased in DCMP patients compared to the controls (P < 0.001 and P < 0.001, respectively). There were positive correlations between CRP, and (r = 0.3.64, P = 0.027) smoking (r = 0.3.56, P = 0.024), and increasing age (r = 0.5, P < 0.001), and negative correlations between CRP, and DBP (r = -0.485, P < 0.001), diameter change (DC; r = -0.493, P < 0.001), AS (r = -0.526, P < 0.001), and AD (r = -0.626, P < 0.001). Conclusion: We have shown that there is a significant relation between high serum CRP levels and impaired aortic stiffness in patients with idiopathic DCMP. These findings may indicate an important role of CRP in the pathogenesis of impaired aortic stiffness in idiopathic DCMP.