Malignant hypertension is characterised by highly elevated blood pressure with papilledema, extravasation and retinal exudates and by hypertensive encephalopathy sings: severe headache, vomiting, vision disorders, paresis, epileptic seizures, in extreme cases – semicoma and coma. Those symptoms are caused by spasm in the cerebral arteries and brain edema. Sometimes autopsy performs plural little thrombi in cerebral arteries. Gallop cardiac and renal insufficiency are also possible to occur. Oligohydruria can be found by the time of diagnostics. Fibroid necrosis of arterial and arteriolar walls is typical, but those changes are reversible depending on treatment. Pathogenesis of malignant hypertension is unknown. Clinical image is determined by two independent processes: cerebral artery dilatation and general fibrinoid degeneration of arteriole walls. Cerebral artery dilatation is caused by loss of self-regulation arterial tone capacity in elevated blood pressure. Excessive cerebral blood flow leads to hypertensive encephalopathy. Generally, excess in renin plasma activity and aldosterone excretion can play a big role in vessels injury.