Purpose: Ambulatory blood pressure monitoring (ABPM) is known to be superior to sphygmomanometer, in defining the parameters of blood pressure and heart rate in normotensive subjects and hypertensive patients. The aim of the present study was to evaluate the blood pressure and heart rate in normotensive subjects by using ABPM devices. Methods: Recordings of 126 normotensive subjects, to whom ABPM was applied for 48 hoıırs in our laboratory between 1998 and 2000, were analyzed retrospectively. Linear (mean, maximum and minimum values) and rhythm analysis (peah, trough, mesor, double amplitude, acrophase, bathyphase and slope values) were performed. Resutis: The mean systolic and diastolic blood pressure values of the subfects were lower than the respective offıce measurements. The average values of blood pressure and heart rate during the activity period were higher than the resting period. Systolic and diastolic blood pressure and heart rate rhythm profıles were almost identical. Conclusion: Blood pressure and heart rate display rhythmic changes vith higher values during the activity period. ABPM recordings provide sufficient data for understanding blood pressure rhythms in normotensive subjects. Understanding and analyzing ABPM data in hypertensive patients ınay also help in developing effıcient treatment strategies.