The aim of the study was evaluation of ACE inhibitors (captopril and ramipril) effect on water-salt homeostasis in the treatment of patients with arterial hypertension (AH) living in the Far North of Russia. 100 male patients with mild and moderate AH were examined 2 weeks, 3 and 6 months after administration of captopril or ramipril. The drugs are shown to correct water-salt metabolism. This is explained by better renal function due to speeding up glomerular filtration and increased sodium excretion with urine, and by activity of humoral mechanisms (inhibited activity of plasma renin, low plasma concentration of aldosterone and its 24-h excretion). Comparison of captopril versus ramipril demonstrates advantages of prolonged ramipril in respect to regulation of water salt metabolism in the treatment of essential hypertension in the Far North.