The effects of 90 Hz and 5 mT EMF on blood Ca++, P+++, Na+, K+ and Cl- levels were investigated. For this purpose, 72 Swiss-Albino mice were used. On days 15. 30 and 45, blood was taken from both the experimental and control groups. A statistically significant decrease in the calcium level was only observed on day 30. On days 15 and 45, a statistically significant increase in the phosphorus level was determined. A significant decrease in the level of plasma potassium and chloride levels and a significant increase in sodium levels were seen throughout the experiment (days 15. 30 and 45).