In a series of studies to explore the relationship of mental stress with blood pressure regulation, we have found that offspring of hypertensive parents exhibit a greater cardiovascular response to the stress of mental arithmetic compared to offspring of normotensive parents. The response is also greater in both adolescents and adults with borderline hypertension. However, there are racial differences in the stress-response pattern. In studying the interaction of sodium sensitivity with stress-reactivity, our data indicates that the cardiovascular response to central stress is not altered by sodium balance. The response to mental stress may be a useful marker for essential hypertension (EH), but does not appear to represent an isolated mechanism in the pathogenesis of EH.