This paper will touch on three points derived from the studies our group has performed by means of continuous 24 hour blood pressure recording in humans. The first point will concern a description of the factors involved in the production of spontaneous blood pressure variability and in particular of our evidence that the magnitude of this phenomenon depends on arterial baroreflexes but also, and perhaps to a larger extent, on central modulation of the cardiovascular system. The second point will deal with the differences in blood pressure variability we have observed in subjects with normal and high blood pressure. Finally, the third point will briefly address the changes in blood pressure variability that take place with ageing.