We have examined the binding of 44% saponin from Panax ginseng, and extracts from Eleuthrococcus senticosus (Siberian ginseng) to classical steroid receptors in vitro. Both extracts had demonstrable affinity for progestin, mineralocorticoid and glucocorticoid receptors; the Siberian ginseng also bound to estrogen receptors. Highest affinity binding was to glucocorticoid receptors, with an approximate Ki of 8×10^-6M for Panax ginseng. Such interactions may explain the reported glucocorticoid-like effects of ginseng in vivo.