A hypertensive emergency is medical condition with severe hypertension involves acute and rapidly progressed target cardiovascular organ damage. This situation requires immediate blood pressure reduction to prevent lethal target-organ damage. A patient must be treated under intensive-care monitoring and with intravenous antihypertensive medicines. To avoid organ ischemia which is caused by rapid reduction in blood pressure, the recommended aims are reduction of mean arterial pressure by no more than 25% during the first one hour, followed by 160/100-110 mmHg within the next 2-6 hours. While a hypertensive urgency which does not accompany any evidence of target-organ damages can be treated with oral antihypertensives agents.