The role of stress in the precipitation of hypertension is often described in clinical studies, although the underlying mechanism remains unknown. The present study concerns the role of electrolytes in stress induced hypertension in rats. Acute immobilization stress of one hour elevated systolic blood pressure (SBP) in rats. Restraint induced blood pressure elevation was associated with increased sodium concentration in the red cells, heart and kidney, and decreased potassium in the red cells. Magnesium concentration increased and calcium concentration decreased in the serum. Increases of calcium and decreases of magnesium were also observed in the heart and kidney tissues. The results may help toward an understanding of the relationship between hypertension and electrolyte homeostasis. A possible role of Na + -K + -ATPase activity leading to observed changes of electrolytes or vice versa is discussed.