Blood pressure variability is a physiological phenomenon influenced by many internal and external factors. This variability could be also influenced by pathological conditions such as arterial hypertension. Two forms must be mainly distinguished: the blood pressure variability at long but also short-term. The latter could only be studied by continuous recordings. From the initial invasive intraarterial approach, it can nowadays be explored by a non invasive system of beat to beat recordings using the infrared photo plethysmography (the FINAPRES system). In this paper, some important questions will be treated such as the interest of measuring blood pressure variability, its cardiovascular prognosis and how therapeutic tools can be applied when it is increased?