In this study, 120 British male mice, weighing 35-40 g, and 5 months old were used. Three groups, one control (Group 1) and two experimental (Groups II and III), were formed. One experimental group (Group II) received 60 Hz and 5 mT, while the other (Group III) received 90 Hz frequency and 5 mT magnetic flux density efficacy electromagnetic field (EMF), between 9(00) and 17(00). During this period, blood was taken every hour and blood electrolyte levels (Ca++, P+++, Na+, K+, Cl-) were evaluated. In conclusion, in almost all periods and groups only sodium and calcium levels showed a steady decrease, while potassium levels increased when compared to the control group. However, these changes were not significant in most periods (p > 0.05).