Ambulatory measurements are increasingly used to evaluate the effects of different aspects of lifestyle on blood pressure. Such measurements provide greater statistical power than casual measurements and are particularly useful for assessing diurnal variations, 24-hour load and variability, and both acute and sustained effects of common behaviours. Concomitant heart rate and biochemical and genetic measurements can provide clues as to the mechanisms underlying the effects of lifestyle on blood pressure in different target populations. The information obtained is proving helpful in evaluating actions and interactions of smoking, alcohol, physical activity, caffeine consumption, various types of psychological stress, obesity, and dietary habits.