In a large group of young (n = 194) and elderly (n = 148) healthy subjects, we explored the relationship between ambulatory blood pressure (BP) levels, within-subject BP variability, and age in men and women. The questions asked were: Do elderly subjects display higher BP levels and variability compared to a young group? Are there gender differences in BP level and variability? Are these gender differences similar in the young and the elderly subjects? Do age or gender influence BP in a similar way during waking and during sleep? Subjects wore an ambulatory BP monitor (Accutracker II) for 24 h.