The aim of the present study was to determine the relationship between the variability in systolic blood pressure and pulse intervals with respect to baroreflex sensitivity, and compare healthy and borderlin hypetensive children. A causal interrelationship between the 0.1 Hz variability of systolic blood pressure and pulse interval variability and BRS was shown. In borderlin hypertesnives, and increased variability of systolic blood pressure might be a sign of and increased sympathetic activity and it explains high Pulse interval variability at low BRS.