To assess the relationship between early clinically detectable involvement of hypertensive vascular disease in heart and kidneys, we obtained systemic and renal hemodynamic and M-mode echocardiographic measurements in 65 patients with essential hypertension. The results indicate that patients with and without left ventricular hypertrophy had similar renal hemodynamic findings. In contrast, patients with altered renal hemodynamic measurements (ie, reduced renal distribution of cardiac output and, therefore, absolute renal blood flow with increased renal vascular resistance) and increased serum uric acid levels also had increased left ventricular posterior and septal wall thicknesses and mass index. Moreover, these data also demonstrated that in patients with altered renal hemodynamics, the lower the renal distribution of cardiac output and the higher the serum uric acid levels, the greater were the indexes of cardiac enlargement. These results demonstrated that the pathophysiological and hemodynamic effects of essential hypertension in the heart precede those in the kidneys.