Hypertension is defined as a sustained increase in systolic (≥140 mmHg), diastolic (≥90 mmHg) or both blood pressures at rest. The most common is hypertension of unknown cause. Hypertension of known cause is called secondary hypertension and may be associated with kidney disease, artery disease, heart diseases, or disease of the endocrine system. Hospitalized patients are more likely to have increased blood pressure because they are exposed to stress, pain, and non-invasive and invasive medical procedures. Perioperative control of blood pressure is very important because in hypertensive patients procedures before, during, and after the operation cause many more variations of blood pressure and heart rate than in normotensive patients. It is very important to prescribe antihypertensives appropriately and at the right time since hypertension in those patients can cause life- threatening conditions. Recent studies have shown that blood pressure decrease has a protective effect on target organs because it reduce the incidence od stroke, myocardial infarction, heart failure, peripheral artery disease, and kidney disease. In addition to antihypertensive therapy, we should not forget lifestyle modifications such as reduced salt intake and smoking cessation.