This study investigates the 24-h blood pressure (BP) pattern in longevous subjects and their progeny, in order to validate the hypothesis that the human beings who live beyond their longest expectancy of life should be protected from developing hypertension. Such a characteristic feature is supposed to be a biological aspect of human longevity which can be transmitted to the progeny. The study was carried out on 92 elderly subjects, (45 M, 47 W, 76-102 years), and 28 firstborn descendants of the first (7 M, 7 W, 36-55 years) and second (7 M, 7 W, 16-26 years) generation, in clinical health. The control subjects were 308 clinically healthy individuals (154 M, 154 F, 16-75 years) of the common population, stratified by age. The longevous subjects were found to show a diastolic daily mean level less pronounced than expected, according to the BP age-related trend in the common population. Both the children and grandchildren of the longevous subjects were seen to show a systolic and diastolic daily mean level significantly less pronounced than in their coeval subjects of the common population. Because of the unexpected lower diastolic BP daily mean level in the very old subjects, the hypothesis that the longevous subjects might be protected from developing hypertension via the arteriolar vasoconstriction seems to be confirmed. Because of the lower systolic and diastolic BP in young and adult subjects with a positive familiarity for longevity, the hypothesis that the hemodynamic protection from senile hypertension might be an inheritable biological feature of the longevity seems to be acceptable.