The aim of this paper was to study the influence of addition of magnesium and calcium salts to high sugar musts on the process of fermentation and biomass growth. Musts containing approximately 310 g⋅total sugar/dm³ were enriched with 240 mg⋅magnesium/dm³ as well as 40 and 400 mg⋅calcium ions/dm³. Yeast Saccharomyces bayanus S.o./1AD were used. It was found, that in applied conditions the most favourable is supplementation with magnesium. In the case of addition of MgSO4 to the musts, the lowest content of extract, the highest efficiency of fermentation – 93% and the highest ethanol content – 16% v/v were stated. However, wine obtained from the must suplemented with 400 mg⋅calcium/dm³ was characterized by both the lowest content of alcohol – 14.1% vol. and the lowest efficiency – 82%. Addition of magnesium and calcium ions to the musts did not influence on the content of total sugar, saccharose, volatile and total acidity, SO₂. After 72 hours of cultivation, the highest biomass growth – 9.2 g d.m.·dm^-3 was obtained from the must enriched with 40 mg⋅calcium·dm^-3, and the lowest amount of biomass -7.7 g d.m.·dm^-3 was stated in medium suplemented with 400 mg⋅calcium·dm^-3.