Differences in 24 h blood pressure (BP) monitoring parameters such as average 24 h BP, day to night BP ratio and BP variability could have an impact in arterial stiffness. The study hypothesis was that despite similar average BP values in ambulatory blood pressure monitoring subjects with increased 24 h BP variability may have increased arterial stiffness. The study population consisted of 115 consecutive young healthy volunteers. Carotid-femoral PWV was measured in all subjects. Clinic BP was measured and an appropriate cuff was fitted on the non-dominant arm of each subject for a 24 h ambulatory blood pressure monitoring session. Waist to hip ratio as well as BMI was measured. Family history and smoking habits were recorded. In univariate analysis, estimated carotid-femoral PWV showed a significant correlation with age, weight, waist circumference, height, clinic systolic and diastolic BP, 24-h systolic and diastolic BP, 24-h pulse pressure, 24-h systolic and diastolic BP variability, daytime systolic and diastolic BP, daytime pulse pressure, daytime systolic and diastolic BP variability, nighttime systolic BP, nighttime pulse pressure and nighttime systolic BP variability. In multivariate regression analysis, age (B=0.95, P<0.001) and 24 h systolic BP variability (B=0.28, P<0.001) were independent determinanats of arterial stiffness. In conclusions, increased 24 h systolic BP variability is associated with arterial stiffness in young healthy volunteers. Pulse wave velocity in a young healthy population is useful to identify determinants of premature arterial stiffness, thus further elucidating the aspects of early vascular ageing.