The influence of regular moderate ethanol consumption on the status of vitamin C was followed in guinea-pigs and rats. In the guinea-pigs examined, 10-day consumption of ethanol (4.5 g per day and kg of body weight), administered in drinking water under a vitamin C-deficient diet, caused a greater decrease in the tissue concentrations and the body-pool of this vitamin than in the group without alcohol. In the rats, on the contrary, the daily consumption of ethanol (6% vol) during 10 months resulted in an increase in the body stores of vitamin C, especially in the liver, adrenals, kidneys, and lungs. Moreover, the biosynthesis of ascorbate from D-glucuronolactone in vitro was more intensive (by 30%) in the liver microsomes of alcoholized rats than in those of controls (without alcohol). These results indicate that the need of vitamin C during chronic consumption of moderate alcohol doses is enhanced. This is due to the participation of ascorbate in oxidoreducing processes connected with ethanol metabolism which leads to its irreversible destruction. In the rat, this loss is compensated by its enhanced biosynthesis, while in the guinea-pig it produces increased demands for its exogenous intake. If these are not satisfied, a partial vitamin C deficiency may occur, which potentiates the harmful effect of alcohol on the health status.