Psychosomatic factors, sympathoneural and sympathoadrenal as well as cardiovascular mechanisms, were studied in 24 patients 18–24 years of age with borderline hypertension, 50 age-matched nonnotensive offspring of hypertensive parents, and 49 controls with no family history of hypertension. They were compared by projective and questionnaire-based psychological tests and their circulatory and neurohormonal reactivity to mental (Stroop color-word conflict test and arithmetic test) and physical stressors (orthostasis and bicycle ergometry test) were measured. Borderline hypertensive subjects externalized aggression less (p< 0.05) but internalized it more (p< 0.05) and were more submissive (p< 0.05) when compared with controls. Offspring of hypertensive parents showed a similar but weaker pattern. Both risk groups reported more positive interactions with their parents (genetic risk subjects versus controls,p< 0.05; borderline hypertensive patients versus controls,p= 0.08) and had higher state-anxiety levels (p< 0.05). There were more subjective symptoms of β-adrenergic receptormediated functions (e.g., tachycardia, tremor) in borderline hypertensive subjects and offspring of hypertensive parents, elevated heart rates (analysis of repeated measures,p< 0.001), and enhanced plasma norepinephrine concentrations (p< 0.05) when compared with controls. These findings in subjects at risk for the development of hypertension suggest that psychosomatic factors and sympathetic overactivity are involved in the early phase of hypertension.