Chronic ethanol consumption consistently resulted in mild hypertension in the male Wistar rats used in the present study. The ethanol-treated animals also have reduced 24-hour urinary output and significant sodium retention when compared to the controls. Total plasma volume was estimated using the technique of indicator dilution, and an increase of 20% was observed in the ethanol-treated animals. Vascular smooth muscle responsiveness to noradrenaline in vitro was not different between the two groups of animals. Therefore the blood pressure elevation in the ethanol-treated animals seems to be associated with sodium retention and plasma volume expansion, and probably is unrelated to altered vascular responsiveness.