Retinoic acid. the active metabolite of vitamin A. was detected in the human liver for the first time using a new method. A rapid and sensitive technique has been developed using gradient-elution. reverse-phase high performance liquid chromatography. This assay. with simultaneous multiwavelength detection at 294nm, 325nm and 450nm after saponifcation of liver samples. allows us seperation and quantitation of vitamin E, retinoic acid, total retinoids and various carotenoids in one small sample. The proportion of retinoic acid to total retinoids in human liver appears to be quite $consistent(2.4pm0.2%$ ). With low vitamin A storage in liver, detection at another wavelenth 354nm would increase the sensitivity for retinoic acid of small quantity This method of analysis could be used for other tissues like red blood cells, plasma or serum, also. Hepatic retinoic acid level with total retinoids and carotenoids would serve a better indicator of functional vitamin A nutriture especially for those with disease requiring needle biopsy of liver.