Magnesium salts are components of many dietary supplements used in treatment or prevention of magnesium deficiency. Hypomagnesemia usually results from an improper lifestyle, including unbalanced diet. Isolated hepatocytes of animals or humans are the preferred model used to study the in vitro effects of exogenous factors on cellular metabolic changes. The aim of this study was to evaluate the content of saturated, monounsaturated and polyunsaturated fatty acids and their esters in isolated rat hepatocytes influenced by different magnesium concentrations. The isolated rat hepatocytes were used as the test material. Hepatocytes were prepared in culture medium (Hepatocyte Medium) + MgCl(2) solution to concentrations of 2 mM/dm(3) MgCl(2), 4 mM/dm(3) MgCl(2). After incubation with different concentrations of magnesium ions, changes in the content of fatty acids and their esters were found for the whole hepatocytes and hepatocyte membranes. Despite changes in the fatty acid content in the whole hepatocytes and their membranes, there were no changes in the coefficient of degree of saturation of fatty acids when different concentrations of MgCl2 were used.