Background: Impaired left ventricular diastolic function is a common finding in essential hypertension. Methods: In order to investigate possible relationships between flow velocity through the mitral valve (E/A; index of left ventricular diastolic function) and 24-hour blood pressure and heart rate variations, 198 patients with mild to moderate essential hypertension were studied by Doppler echocardiography and ambulatory blood pressure monitoring. They were divided according to age into group 1 (n = 88, age 40–54 years) and group 2 (n = 110, age 55–79 years). Each group was divided into subgroups with (1a, 2a) or without (1b, 2b) left ventricular hypertrophy according to the end-diastolic posterior wall thickness and/or the interventricular septum thickness. Results: In a multivariate stepwise regression analysis, age (β = –0.25, p < 0.0001), posterior wall thickness (β = –0.31, p < 0.0057) and mean heart rate during the day (β = –0.34, p < 0.0284) were the independent predictors of E/A in the pooled population. In group 1a (young subjects with left ventricular hypertrophy), mean systolic blood pressure during the night (β = –0.33, p < 0.041) was the only independent predictor of E/A. In the elderly group without left ventricular hypertrophy (group 2b), the mean heart rate during the day (β = –0.44, p < 0.0000) and mean pulse pressure during the night (β = –0.60, p < 0.0007) were the independent predictors of E/A. Conclusions: The new finding provided by this study is that in elderly hypertensive patients without left ventricular hypertrophy, a large pulse pressure at night may serve as an independent predictor of abnormal left ventricular diastolic filling.