Isoflavones prevent the incidence of cancer, reduce cardiovascular problems, and decrease menopausal symptoms. In soybean (Glycine soja Sieb. & Zucc.) seeds, the content is greatly affected by growing conditions. The variations in soy-isoflavone content were investigated by growing 346 Korean wild soybean accessions from natural habitats under the same agroclimatic conditions. High-performance liquid chromatography was used to measure the profiles of six soy-isoflavones, i.e. glycosides (daidzin, glycitin, genistin) and malonyl glycosides (malonyl-daidzin, malonyl-glycitin, and malonyl-genistin). The soy-isoflavone content of the wild soybeans ranged from 0.5 to 5.51 mg/g with an average of 2.78 mg/g. The highest mean total soy-isoflavone was genistin (1.393 mg/g), followed by daidzin (0.939 mg/g) and glycitin (0.250 mg/g). Korean wild soybean seeds examined in this study were rich in malonyl-genistin. An increasing trend for total soy-isoflavone content was observed from the north to the southeast in the geographical distribution sites, which signifies the effect of genotype and collection site. The information generated in this report will greatly aid soybean breeding stratagems aimed at improving soy-isoflavone concentration in soybean seeds.