In an attempt to evaluate the various serum hormonal changes in terminal renal failure, the fasting $T_4,;T_3,;rT_3$, gastrin, secretin prolactin, and aldosterone were measured by radioimmunoassay in 12 patients with chronic renal failure, who were admitted to Chosun University Hospital from January to June, 1981. From the analysis the following results were obtained. 1. Mean values of serum hormonal concentration in 10 normal control were as follows: $T_4,;12.93{pm}2.00ug/ml$; $T_3,;113.0{pm}28.7ng/ml$; $rT_3,;0.11{pm}0.10ng/ml$; gastrin, $100.0{pm}47.1pg/ml$; secretin, $32.46{pm}11.45pg/ml$; prolactin, $11.0{pm}3.6ng/ml$; aldosterone, $137.0{pm}58.5pg/ml$, 2. Mean values of serum hormonal concentration in 12 chronic renal failure were as follows: $T_4,;7.34{pm}2.43ug/ml$; $T_3,;71.0{pm}19.1ng/ml$; reverse $T_3,;0.38{pm}0.19ng/ml$; gastrin, $162.5{pm}40.2pg/ml$; secretin, $107.50{pm}20.48pg/ml$; prolactin, $34.0{pm}17.2ng/ml$; Aldosterone, $86.5{pm}19.8pg/ml$. 3. In chronic renal failure group, serum T 4, T 3 and adosterone level were significantly lower than those of the control group, but serum $rT_3$, gastrin, secretin and prolactin were significantly higher than those of the control group. 4. In the view of the correlation between serum hormonal concentions and serum creatinine levels in patients with chronic renal failure, $rT_3$, gastrin, secretin and prolactin showed increasing tendency(positive correlations), whereas $T_4,;T_3$ and aldosterone showed decreasing tendency (negative correlations) with increment of serum cteatinine levels. And so, we observed the negative correlation between $T_3;and;rT_3$.