Acute hypertensive emergencies occur in 5 to 35 % of the patients in perioperative care. This is associated with an increase in perioperative complications: the rate of bleedings, myocardial infarctions, cerebral ischemia and overall mortality is increased 4-fold. Before an operation, it is of utmost importance to recognize predictors for hypertensive emergencies and to achieve an adequate blood pressure control. There has so far been no agreement on a blood pressure threshold at which blood pressure needs to be reduced. Antihypertensive therapy is a bedside decision of the responsible physician. It aims at a rapid decrease of hypertensive peaks without risking a reduced organ perfusion. The optimal drug for the treating hypertensive emergencies should have a rapid and safe action. Antihypertensives of first choice are esmolol, metoprolol, urapidil or clonidin. The oral therapy with nifedipine or nitrendipine has the risk of abrupt hypotensive episodes and should therefore only be administered after exclusion of an acute coronary syndrome or cardiac failure Because of its toxicity sodium nitroprusside is an antihypertensive drug of second choice. Nitrates or diuretics are supplementary drugs for patients with angina pectoris, cardiac failure or renal insufficiency. Newer substances (fenoldopam, nicardipine, clevidipine) have promising kinetic properties but are not as yet been approved for antihypertensive treatment in Germany.