The principal aim of the present study was to determine the relationship of ambulatory blood pressure (BP) to urinary electrolyte excretion in normotensives. Twenty-five young adults underwent ambulatory BP and heart rate monitoring while collecting urine over 24 h. The correlations of 24 h urine sodium excretion and the ratio of sodium/potassium excretion with systolic BP in the laboratory (r = 0.12 and 0.24), ambulatory awake (r = 0.11 and 0.24), and ambulatory asleep (r = 0.24 and 0.31) settings were all in the positive direction but not significant. However, 24 h sodium excretion did correlate significantly and positively with awake and asleep ambulatory systolic (r = 0.45 and 0.41, P < .05) and diastolic (r = 0.42 and 0.43, P < .05) coefficients of variability. Thus, in normotensives on an unlimited diet, 24 h urinary sodium was more closely related to ambulatory BP variability than to BP level.