Hypertension is more prevalent and more severe in African Americans compared with whites. Evidence is presented that support an important role of the kidney in the excess incidence of hypertension in this population group. There are quantitative differences in renal physiology between hypertensive African Americans and whites, the most dominant of which is an increased renal vascular resistance in African Americans that might be either structural or functional. This increased renal vascular resistance might represent an underlying primary renal disease that has remained concealed among the spectrum of diseases referred to as benign nephrosclerosis. The answer(s) to this intriguing question will provide a better understanding of the kidney as a mediator and/or target of hypertension.