Magnesium plays very important metabolic and regulatory roles in the animal organism. On this element tissues' concentration may have an influence other factors, such as sex hormones and vitamin E. The aim of our paper was to determine the influence of various testosterone doses given to male rats and various estradiol doses given to female rats on tissue magnesium concentration. Moreover, we analysed the influence of vitamin E applied with sex hormones on magnesium concentration in the tested groups of male and female rats. Testosterone was given to male rats at the doses of 0.01 mg kg(-1) of b.w. and 0.1 mg kg(-1) of b.w. Estradiol was given to female rats at the doses of 0.01 mg kg(-1) of b.w. and 0.1 mg kg(-1) of b.w. Some groups of animals additionally received vitamin E at the dose of 100 mg kg(-1) of b.w. The experiment was conducted for two weeks and next the brain, liver, kidneys and heart were taken for analysis. Tissue magnesium concentration was studied. We showed that sex hormones (estradiol in females, testosterone in males) influenced magnesium concentration reduction in the tested tissues. This decrease depended on the dose of applied hormone and only insignificantly on its kind. It was showed that simultaneously applied vitamin E diminished the effect of sex hormones action on magnesium concentration in the tested tissues.