The expression 'hypertensive urgencies' includes many diseases. The unifying features of these diseases are a high level of arterial pressure and acute distress of one or more organs. The aim of the review was to define the idea of the 'acute hypertension' as a new concept, different from 'chronic hypertension'. Acute hypertension might be related to 'organ damage' because it is the cause, the consequence or an effect of the acute stress. We compounded a narrative review which has included analyses of 373 articles. The structure of the search strategy included a literature search of PubMed, MEDLINE, Cochrane Library and Google Scholar databases. We applied the following inclusion criteria: prospective double-blind randomised controlled trials, experimental animal work studies, case-control studies and recruiting patients representative of the general sick population. In this review, the diseases included in the term 'hypertensive emergencies' share 'acut' hypertension. This is a new idea that emphasises the suddenly increased arterial pressure, irrespective of the initial arterial pressure and independent of the goals of hypertension control. The 'hypertensive emergencies' have been grouped together in three subsets: (1) diseases that result from acute hypertension that is caused by faulty regulation of the peripheral circulation (acute primary hypertension), (2) diseases that produce hypertension (acute secondary hypertension) and 3) diseases that have hypertension as an effect of the acute stress caused by the principle disease (acute associated hypertension). This review highlights a novel idea: acute hypertension is a common sign of different diseases characterised by the sudden surge of arterial pressure, so overwhelming the difference between hypertensive emergencies and urgencies. The judgment of acute hypertension is independent of the initial arterial pressure, normotension or hypertension and is linked with the transient failure of the baroreflex. Hypertensive emergencies are grouped together because all of these diseases require prompt therapy to prevent the negative outcomes of acute hypertension.