Abstract: A rapid, sensitive, specific and valid radioimmuoassay for chendeoxycholylglycine （CDCG） in serum has been developed. The antiserum was abtained from rabbits injected with bovine serum albumin conjugates of CDCG. The minimum detectable value was 0.3 Pmol per tube. Recovery expressing the accurasy of the method was determined to be 92.6-103.9%.The mean coefficient variation of interassay and between assays were. 5.3% and 11%, respectively.In our study the fasting serum CDCG in 121 normal adults was 3.07±1.5 nmol/ml. The concentration of CDCG in serum was significantly increased in various liver diseases and its measurement appeared to be an extremely sensitive indicator of liver functions.