This study was investigated that effects of steroid hormones on serum sodium and potassium concentration in parathyroidectomized chickens. The results are as followings; 1) Serum sodium and potassium concentration in SHAM-controls were unchanged. 2) In parathyroidectomized chickens, serum potassium level increased more than that of control and serum sodium level appeared no change in each group. 3) In group of administration of cortisone in parathyroidectomized chickens, serum potassium level increased generally more than that of control and serum sodium level appeared no change in each group. 4) In group of administration of testosterone in parathyroidectomized chickens, serum potassium level increased generally more than that of control and serum sodium level revealed no change in each group.