In Peucedanum japonicum and Aster tataricus L. chlorogenic acid was identified by methods of P.P.C. and T.L.C. $L-Phenylalanine-U-^{14}C;and;sodium;acetate-2-^{14}C$ were administered to Peucedanum japonicum, $L-Tyrosine-U-^{14}C$ to Aster tataricus and $caffeic;acid-carboxyl-^{14}C;and;L-tyrosine-U-^{14}C$ to Fagopyrum esculentum $M_{OENCH}$. The incorporation of each compound into chlorogenic acid was compared. $L-Phenylalanine-U-^{14}C$ showed higher incorporation to chlorogenic acid than sodium $acetate-2-^{14}C$ in Peucedanum japonicum. $Caffeic{;}acid-carboxyl-^{14}C$ was higher to chlorogenic acid than $L-tyrosine-U-^{14}C$ in Fagopyrum esculentum. $L-Tyrosine-U-^{14}C$ was comparatively low in Aster tataricus.