Isoflavonoids (daidzein, genistein, daidzin, genistin and puerarin) were extracted and analyzed quantitatively by high pressure liquid chromatography from different organs of kudzu vine (Pueraria montana) and starch samples derived from kudzu roots. Aerial parts of kudzu plants (young shoots, leaf blades and leaf petioles) contained relatively low levels of all isoflavonoids examined, whereas seeds and seedlings were intermediate in isoflavonoid levels and roots consistently had the highest levels, particularly puerarin and the glucosyl conjugates of genistein and daidzein, namely, genistin and daidzin. Interestingly, commercially available kudzu root starch from Japan does not contain the isoflavonoids of interest, whereas homemade kudzu root starch contains all studied isoflavonoids in various amounts, and especially, high levels of puerarin. Shoots of light-grown kudzu seedlings, when compared with shoots of dark-grown seedlings had higher levels of all isoflavonoids with the exception of daidzin. In contrast, for seedling roots, such differences were not greatly different between light-grown and dark-grown plants. Light-grown intact kudzu seedlings had significantly higher levels of soluble proteins than dark-grown seedlings. Mass spectrometer analyzes of all kudzu samples for the toxic non-protein amino acid, l-canavanine, indicated it to be absent using this method of detection and level of sensitivity.