High blood pressure levels are frequently encountered in medical practice, whether in an outpatient or inpatient setting. It is imperative to quickly differentiate severe hypertension associated with target organ damage, from severe hypertension without acute organ damage. In the latter situation, the management can be done on an outpatient basis by prescribing oral antihypertensive treatment with a close follow-up. On the other hand, in severe hypertension with acute target organ damage, patients should be admitted in an intensive care unit for close monitoring and, in most cases, treated with intravenous antihypertensive treatment. This article reviews the new definitions and management of these two entities and is addressed to both general practitioner and emergency doctor.