Aims: To investigate the value of B-type natriuretic peptide (BNP) in diagnosing left ventricular diastolic dysfunction in patients with hypertension. Methods: The left ventricular diastolic function and plasma BNP levels were assessed prospectively in 135 hypertensive patients. Results: The plasma BNP in patients with (n=61) and without (n=74) diastolic dysfunction was 122±105 and 18±16 pg/ml, respectively (p<0.001). Increased BNP levels were associated with systolic blood pressure (p<0.05), left ventricular mass index (p<0.001), the E/A ratio of transmitral flow (p<0.01) and the isovolumic relaxation time (p<0.01). A receiver-operator characteristic curve showing the sensitivity and specificity of BNP against the echocardiography diagnosis of diastolic dysfunction revealed an area under the curve (accuracy) of 0.904 (p<0.01). Using a cut-off value of >40 pg/ml, the sensitivity and specificity of plasma BNP in diagnosing left ventricular diastolic dysfunction were 79% and 92%, respectively. Conclusions: The plasma BNP levels in patients with hypertension are closely related to left ventricular hypertrophy and filling impairment. Plasma BNP may be used to facilitate the diagnosis of left ventricular diastolic dysfunction.