Black Americans are more susceptible to hypertension and to renal disease than white Americans. Both normotensive and hypertensive blacks are more apt to have salt-sensitive blood pressure responses to the challenge of a salt load than whites. Moreover, salt sensitivity of blood pressure in both normotensive and hypertensive subjects is associated with a decreased excretory capacity for sodium, implicating the kidney in this phenomenon. Salt sensitivity of blood pressure also is associated with increasing age and, in normotensive subjects, may predict the subsequent development of hypertension. Radical differences in a variety of humoral as well as hemodynamic responses to physical and mental stressors have been identified. The relationships between these observations and renal sodium handling require further investigation.