1. Rats toxicated with mercury showed drastic fall in growth rate and supplementation of L-ascorbic acid to these rats could not reverse this effect. The contents of L-ascorbic acid and of D-glucuronic acid in the urine of the toxicated animals were decreased which could be counteracted by subsequent L-ascorbic acid supplementation. 2. The concentration of L-ascorbic acid in the liver tissues of mercury toxicated rats was decreased markedly and administration of L-ascorbic acid to this group could raise the tissue reserve considerably. 3. Severe damages of the normal histological pattern of the kidney tissues of rats viz. cellular and glomerular degeneration were observed under mercury toxicity. 4. In the liver tissues of the mercury toxicated rats, the rate of L-ascorbic acid synthesis was reduced along with increased catabolism of L-ascorbic acid. Subsequent supplementation of L-ascorbic acid to these toxicated rats was, however, found to be effective in reversing these alterations almost to the basal level.