Objective:To study the thyroid function of the patients with chronic renal failure. Methods: The contents of serum thyroid hormones were simultaneously detected by RIA in 27 renal sufficiency stage patients,26 renal insufficiency stage,32 preuremic stage,35 uremia stage,30 healthy persons. Results: Levels of T3,T4,free T3 and free T4 had negative correlation with severity of chronic renal failure.Incidence rates of low T3 and low T4 syndrome had positive correlation with severity of chronic renal failure.While levels of reverse T3 and TSH among the five groups were not seignficant. Conclusion: The serum thyroid hormone was useful in evaluating and treating the patients with chronic renal failure.