In hospital as well as in the office, the physician is often confronted with clinical situations in which blood pressure values are very high. In each case, he will have to evaluate rapidly the degree of emergency and the need for immediate antihypertensive therapy. In the last few years, the therapeutic approach to some hypertensive emergencies has changed. The purpose of the present article is to review: 1) the clinical situations where immediate control of blood pressure is necessary, 2) the present therapeutic approaches and 3) the cardiac and cerebral risks linked to an excessive and too rapid fall in blood pressure.