Thirty (16 male and 14 female) black subjects with a parental history of hypertension (FH) were matched in sex and age with 30 subjects without family history of hypertension (NFH). These two subgroups of black Zimbabweans were matched in number, sex and age and compared to FH and NFH subgroups of healthy, young white subjects. The relationship between parental history of hypertension and cardiovascular reactivity to alpha- and beta-adrenergic stressors was estimated by using cold pressure and mental stressor tests respectively. Black-white differences in cardiovascular reactivity were found. Blacks at risk of getting hypertension showed greater vascular response to the cold pressor, which produces an alpha-adrenergic increase of vascular resistance, compared with the respective whites with parental history of hypertension who showed exaggerated reactivity to mental stressor, a beta-adrenergic activator that enhances cardiovascular reactivity via increases in cardiac output.