In a population with high sodium consumption, we assessed relation between brachial and central blood pressures, elastic properties of large arteries, echocardiographic left ventricular diastolic function and sodium reabsorption as fractional urinary lithium excretion in proximal (FELi) and fractional sodium reabsorption in distal tubules assessed using the endogenous lithium clearance. Mean±s.d. age of 131 treated hypertensive patients (66 men and 65 women) was 61.9±7.5 years. We found significant interaction between left ventricular diastolic function and FELi with respect to the values of brachial blood pressure: systolic (SBP), diastolic (DBP) and mean blood pressure (MBP) (all PINT<0.03). In patients with FELi below the median value and impaired left ventricular diastolic function, the values of SBP (149.3 vs 132.5 mm Hg; P=0.005), DBP (85.1 vs 76.1 mm Hg; P=0.001), MBP (106.5 vs 94.9 mm Hg; P=0.001), central SBP (SBPC) (137.4 vs 122.0 mm Hg; P=0.01), central DBP (DBPC) (84.8 vs 76.0 mm Hg; P=0.003), central MBP (MBPC) (106.9 vs 95.9 mm Hg; P=0.007), aortic pulse wave augmentation (18.0 vs 13.5 mm Hg; P=0.03), pulse wave velocity (14.6 vs 12.5 m s(-1); P=0.02) and central aortic pulse wave augmentation index (155.7% vs 140.9%; P=0.01) were significantly higher than in patients with normal left ventricular diastolic function. Such relationships were not observed in the entire group and patients with FELi above the median value. In the hypertensive population with high sodium intake, increased sodium reabsorption in proximal tubules may affect blood pressure parameters and arterial wall damage, thus contributing to the development of left ventricular diastolic function impairment.