The concentrations of serum calcium, inorganic phosphorus, sodium and potassium from 24 cows with left displacement of abomasum and 21 cows with right displacement of abomasum on pre and postoperation were determined. 1. The preoperative levels of serum calcium in left and right displacement of abomasum were below normal and returned to normal levels postoperatively. 2. The preoperative levels of serum inorganic phosphorus in left and right displacement of abomasum showed slight increase preoperatively and consistent slight rise postoperatively. 3. The preoperative levels of serum sodium in left and right displacement of abomasum were slightly below normal and maintained low levels postoperatively. 4. The preoperative levels of serum patassium in left and right displacement of abomasum were low normal limit and increased to upper normal limit postoperatively.