Critical cases of high blood pressure are common clinical occurrences that may account for as many as 25% of all medical emergencies. About 75% of these increases in blood pressure can be judged as hypertensive urgencies, 25% are even hypertensive emergency situations. Nevertheless, only less than 1% of the hypertensive population experiences hypertensive urgency or emergency situations. Hypertensive emergencies are defined as acute cardiac, vascular or cerebral target organ damages. In these cases an acute lowering of blood pressure is inevitable. The rate and intensity of blood pressure depression is dependent on the localization of organ damages. For cardiac and vascular damages it is absolutely necessary to lower the blood pressure rapidly to near normal values. On the contrary, cerebral organ damages are better treated by a moderate lowering of blood pressure peaks to slightly increased blood pressure levels. In hypertensive urgencies no target organ damages occur. For these patients a slow lowering of blood pressure values to normal levels is adequate.