Hypertension is a common disease, the most common chronic disease. Hypertensive emergency is much less frequent and only affects 1 to 2 % of all hypertensive patients. The true hypertensive emergency is characterized by the serious damage of one hypertensive target organ and requires an urgent intravenous treatment. Isolated blood pressure elevation should not be regarded as a hypertensive emergency if there is no target organ damage, even if the blood pressure is very high. These situations of "false hypertensive emergency", or hypertensive urgencies, often requires an immediate treatment, but oral. Signs of visceral pain of true hypertensive emergency often are a poor general condition, severe headache, decreased visual acuity, neurological deficit of ischemic or hemorrhagic cause, confusion, dyspnea with orthopnoea revealing heart failure, angina, chest pain revealing an aortic dissection, proteinuria, acute renal failure or eclampsia. True hypertensive emergencies include several entities, namely: severe hypertension, malignant hypertension and accelerated hypertension. If malignant hypertension is not treated, the prognosis is poor with 50 % death risk in the following year.