Abstract: The paper dealed with the results of measurments of atrial natriuretic peptide（ANP）in plasma and Na K Cl in serum and urine in 30 patients with hyperthyroidism.The levels of plasma ANP and serum Na in the patients were significantly higher than those in controls.The levels of in serum Cl between the two groups.The levels of plasma ANP and serum Na in 15 patients after 4—5 weeks of antithyroid drug treatment significantly declined and the levels of serum K significantly rose as compaired with those before the treatment.There was a positive correlation between the levels of serum T3 and plasma ANP or between plasma ANP levels and 24-h urine volums.Mechanism,relationship and significance of alterations of ANP and electrolytes in hyperthyroid patients were discussed.