Objective To assess whether serum uric acid, which is a marker of impaired oxidative metabolism, might correlate with left ventricular systolic and diastolic dysfunction in patients with chronic heart failure (CHF). Background Uric acid levels, which are frequently elevated in patients with CHF, correlate with leg vascular resistance. The effects of elevated levels of uric acid on cardiac function in patients with CHF have never been evaluated. Methods We studied 150 outpatients with CHF who came to our heart failure clinic. Patients underwent a complete echo-Doppler examination, with measurement of mitral E wave and mitral A wave velocities, E/A ratio, E wave deceleration time (DtE), left ventricular volumes, ejection fraction, and stroke volume. A restrictive mitral filling pattern (RMFP) was defined as either E/A ratio >2 or E/A >1 and DtE <140 milliseconds. Results Mean age was 62.2 ± 7.8 years (86% male); 24 patients (16%) had an RMFP. Patients with an RMFP had significantly higher uric acid levels compared with patients without RMFP (0.48 ± 0.14 mmol/L vs 0.38 ± 0.08 mmol/L, respectively, P <.001). Uric acid levels correlated significantly with mitral E wave velocity (r =.22, P <.01), E/A ratio (r =.21, P <.05), DtE (r =.26, P <.01), and RMFP (P =.0001). There was no correlation between uric acid and left ventricular volumes, ejection fraction, or stroke volume. In a multivariate model, uric acid predicted DtE independently of renal function, diuretic dose, and left ventricular volumes. Conclusion Elevated uric acid levels are associated with diastolic dysfunction in CHF. Xanthine oxydase inhibition in patients with CHF might theoretically result in an improvement of diastolic function. (Am Heart J 2002;143:1107-11.)