Hypertensive crisis is defined as a severe elevation in BP, such as a diastolic BP above 120 to 130 mm Hg, and is classified as either urgency or emergency. Hypertensive urgency is said to be present when severe elevation in BP is not associated with end-organ injury. There is no scientific evidence that acute BP lowering is beneficial in hypertensive urgency. To the contrary, rapid uncontrolled pressure reduction may be harmful because it can precipitate acute ischemic stroke or myocardial infarction. Therefore, the appropriate approach for patients with hypertensive urgency is to lower the BP more gradually over 24-48 hours with oral antihypertensive agents. Any drug that lowers BP precipitously should be avoided. When the cause of transient BP elevations is easily identified, such as pain or acute anxiety (as in panic disorders), the appropriate therapy is analgesic or anxiolytic medication. When the cause of BP elevation is unknown, various oral antihypertensive agents are available. In contrast to a hypertensive urgency, a hypertensive emergency is relatively and said to be present only when BP elevation confers an immediate threat to the integrity of the cardiovascular system. Patients with a hypertensive emergency require an immediate reduction in BP to avoid further end-organ damage. This is generally accomplished by intravenous therapy in an intensive care setting. Few, if any, comparative or randomized trials provide definitive conclusions about the comparative efficacy and safety of antihypertensive drugs. Some investigators recommend decreasing the diastolic BP to no less than 100-110 mm Hg. A reasonable approach for most patients with hypertensive emergencies is to lower the mean arterial pressure by 25% over the initial 2-4 hours with the clinically most appropriate antihypertensive regimen.