Abstract: Objective To study the relationship beuween metabolizing disorder of serum thyroxin and the degree of liver damage in patients with grave viral hepatitis and its clinical significance.Methods Using radiation immune assay (RIA) to detect of serum thyroxin of 54 patients with grave viral hepatitis, 41 patients with acute hepatitis and 30 contrasts.Results Serum T3, T4, TSH in patients with grave viral hepatitis is significantly lower than that in patients with acute hepatitis and contrasts (P<0.05) , and the level of serum rT3 is significantly higher (P<0.05) .Serum T3, T4 and albumin are positive correlation, T3, TSH and PT, rT3 and ALT are negative correlation.Serum T3, T4 and TSH in patients who died of grave viral hepatitis is significantly lower than survival (P<0.01) , and serum rT3 is significantly higher (P<0.01) .Conclusion Serum thyroxin is significantly disorder in patients with grave viral hepatitis, and the more serious the state is, the worse the prognosis is.The Serum thyroxin is a sensitive index, which can reflect liver function, and is helpful for judging the degree of hepatitis and its prognosis.