In recent decades, the incidence and prevalence of arterial hypertension has been increasing both in the world and in the Republic of Croatia and represents a major public health problem. Almost every year, the healthcare system is faced with an epidemic of influenza, and in the last few years with an new epidemic of the Covid-19 disease caused by the SARS-CoV-2 virus. Hypertension is one of the most important risk factor for the development of severe forms of Covid-19 disease and influenza. On the other hand, after the recovery from these diseases the onset of the de novo development or worsening of existing hypertension is noticed. The association of influenza with the onset of arterial hypertension has been known for many years and occurs in about 16% of hospitalized and about 5% of non-hospitalized patients after the recovery from the flu. More recently, an even higher and more significant incidence of hypertension has been noticed after the Covid-19 disease and occurs in about 21% of hospitalized and 16% of non-hospitalized patients. Pathogenetic mechanisms of the development of hypertension after influenza have not been fully elucidated. It is most likely the interference of viral proteins with the transcription of the ACE 2 (angiotensin converting enzyme 2) gene into a protein. In the case of SARS-CoV-2 viral infection, numerous studies show the destruction of the ACE 2 enzyme expression by the binding of the viral spike protein to this receptor. The ACE 2 enzyme is crucial in the activation of the counter-regulatory mechanism of the renin-angiotensin-aldosterone system (RAAS) that lowers arterial pressure. This mechanism involves the formation and function of angiotensin peptides, especially peptides 1-7. Loss of ACE 2 function leads to the predominance of the classic part of the RAAS system and the prohypertensive effects of angiotensin II and the development of hypertension. Similar effects to SARS-CoV-2 infection are also shown by vector vaccines against Covid-19 disease. They stimulate the synthesis of the spike protein of the coronavirus according to the genetic instructions they carry. Spike proteins in this free, soluble form can bind to ACE 2 and reduce its expression, thereby causing hypertension. It was observed in about 4% individuals, while the proportion of hypertension of the III degree and emergency cases related to hypertension was recorded in 0.6% of the vaccinated individuals. The significance of this unwanted vaccine effect is important considering the wide vaccination coverage of about 67% of the world's population and delivered 13.59 billion doses of the Covid-19 vaccine.