Magnesium and calcium are essential plant macroelements that in some cases can have antagonistic relation in soil. Calcium primary has structural role in plants, while magnesium is a part of chlorophyll. Although calcium can naturally be found in soil in respected amounts and it is not necessary to use fertilizers containing calcium, sometimes it is better to perform foliar nutrition, particularly in case of fruit vegetables, such as bell pepper. Calcium deficiency leads to poor visual and nutritive quality of the fruit. Foliar nutrition also affects uptake of other macroelements like magnesium and and thus to the total mineral composition of the bell pepper fruit. Goal in this paper is to determine the effect of foliar nutrition containing calcium on magnesium content in bell pepper fruits. Field fertilization experiment by the method of Random block design in 3 replications was carried out with two cultivars of bell pepper (Capsicum annuum L.) ('Šorokšari' and 'Kurtovska kapija'). The experiment included 4 foliar fertilization treatments with calcium biostimulants (control - application of water only, Ecogreen 3 g/L - lower concentration, Ecogreen 5 g/L - higher concentration and Zeogreen + P 5 g/L). Results show that in case of 'Kurtovska kapija' cultivar higher dry matter content was determined compared to control tretament, while in case of 'Šorokšari' cultivar no difference was determined. Further, positive effect of the treatment was obtained in bell pepper magnesium dry matter content in 'Šorokšari' cultivar and negative effect in 'Kurtovska kapija' cultivar compared to control treatment. In both cultivars positive the effect of treatment on bell pepper magnesium fresh matter content was observed.