High blood pressure or primary essential hypertension, or arterial hypertension (AH), or hypertension alone is a chronic disease with the highest incidence in the world. The main characteristic of hypertension is the increase in systolic and particularly, in diastolic arterial pressure. AH is essential (primary) in 90–95% of the cases and secondary in the rest 5–10%. In industrialized countries, every fifth adult is hypertensive (1, 2, 3). The disease is common in both developed (333 million hypertensives) and developing countries (639 million hypertensives). However, the number of hypertensives varies considerably in the different regions. It is the lowest – 3.4% (men) and 6.8% (women) – in the rural regions of India and the highest – 68.9% (men) and 72.5% (women) – in Poland. By 2025, AH will rise by only 5.7% in the EU, but the number of people living with hypertension will increase by 15.3%. Hypertension is the most important preventable risk factor for premature death worldwide.