Seventeen normals (mean age, 34 +/- 4.31 years) and thirteen borderline hypertensives (BH) (mean age, 33 +/- 4.6), immune from any other pathology, were tested (standing-up test) in order to assess possible parasympathetic dysfunctions in young BH, not preselected as hyperkinetic subjects. Curves of heart rate (HR) variations were monitored by electrocardiogram during the test with an exhaustive analysis carried out to obtain indexes showing the whole trend as well as the 30 degrees/15 degrees ratio. No significant difference emerges between the two groups when mean values of such parameters are compared. It is concluded that parasympathetic dysfunctions do not occur in BH patients.