We examined the racial differences in left ventricular (LV) geometric pattern in relation to 24-hour ambulatory blood pressure (BP) monitoring and the presence or absence of a nocturnal BP dip. Our study confirms the blunting of nocturnal BP dip among black hypertensives. Body mass index, rather than race, was a major determinant of left ventricular hypertrophy. We did not observe a difference in prevalence of left ventricular hypertrophy by race. However, left ventricular adaptation to hypertension differed in hypertensive black and white individuals; whereas most of the white patients with Stage 1-2 hypertension had a normal ventricular pattern, LV concentric remodeling and concentric hypertrophy were the most common adaptive ventricular patterns in blacks with Stage 1-2 hypertension. A six-fold higher prevalence of concentric remodeling was observed in blacks as compared with whites. The impaired nocturnal BP dip in blacks may contribute to the different hemodynamic pattern. Determinants of myocardial oxygen consumption were significantly higher in black hypertensives.