In 142 Wistar rats fed high (30% kcal) or low (7% kcal) fat diet the effect of various amounts of magnesium and calcium on blood pressure was studied. The animals were divided into 19 groups consisting of 6—8 rats, which consumed experimental or control diet for 6 weeks. Two experiments were performed on the high fat diet. In experiment I six groups of animals received a diet with 0.04% magnesium, 0.15% magnesium, 0.3% magnesium, 2.0% calcium, 4.0% calcium, or 0.3% magnesium + 0.9% calcium respectively. In experiment II the other six groups of animals were kept on the same diets. In the first experiment the rats drank water, in the second water with 1.5% NaCl. In experiment III, on the low fat diet, three groups of animals were fed a diet with 0.3% magnesium, 2.0% calcium or 4.0% calcium respectively. The rats drank water. A reducing blood pressure effect of magnesium, calcium and both minerals together in rats fed the high fat diet in both models of experiment was found. However, it should be mentioned that the effect was more pronounced in NaCl induced arterial hypertension. The addition of these minerals to the low fat diet did not influence blood pressure. Diet supplementation with calcium and/or magnesium influenced ascorbic acid metabolism by decreaseing urine output and increasing its content in some tissues. Rats with experimental hypertension excreated greater amounts of PGF2 in urine in relation to the control group.