Left ventricular (LV) diastolic filling was examined by Doppler echocardiography in 239 patients with essential hypertension and 100 normal subjects. The Doppler study showed an inverse correlation between age and early diastolic peak velocity (PVE, r-0.201, P less than 0.05) [and a positive correlation between age and late diastolic peak velocity (PVA, r = 0.202, P less than 0.05) in normal subjects. Isovolumic relaxation time and late diastolic filling time were prolonged, PVA, A/E and Ai elevated, PVE, E/A and Ei/Ai as well as total filling time decreased in patients with hypertension as compared with the values found in the normal subjects (P less than 0.05 to 0.01). The results showed definite impairement of LV diastolic function in hypertensive patients. PVA correlated positively with systolic blood pressure (r = 0.68, P less than 0.01) and modestly with left atrial dimension in the hypertensives. No significant differences were found in FS and EF between the two study populations, indicating that LV filling abnormalities may occur early in patients with hypertension, even at a time when systolic performance has not yet been affected.