Herbal medicines are medicinal products containing a single or a mixture of two or more different herbal substances or herbal preparations as active principles. Recently, much attention has been paid to developing various kinds of fermented herbal extracts, a new type of traditional herbal medicine in the field of Korean traditional medicine. The fermentation of medicinal herbs is intended to exert a favorable influence on bioestability, bioavaliablilty and pharmacological activity of herbal extract in the gastrointestinal tract as well as intensifying the nutritional and pharmacological aspects of the medicinal herbs. The purpose of this study was to investigate biological activities of fermented Rehmanniae Radix by lactic acid bacteria at $30^{circ}C$ for 3 days in comparison with those for Rehmanniae Radix The fermented Rehmanniae Radix exhibited different chemical profile to Rehmanniae Radix generated with HPLC, indicating production of new ingredients during fermentation. Rehmanniae Radix served as good nutritional sources for the growth of lactic acid bacteria showing increased number of bacteria during fermentation. Toxic effect of the fermented Rehmanniae Radix to cells were not seen judged by the MTT assay. The fermented Rehmanniae Radix exhibited better antioxidant effect than non-fermented Rehmanniae Radix analyzed by a SOD-likely assay. Both hypoglycemic and hypotensive effects of the fermented Rehmanniae Radix were also detected and better than those for Rehmanniae Radix in showing dose-dependent inhibitory effects on alpha-glucosidase and ACE, respectively. In conclusion, fermented Rehmanniae Radix appears to have more biological activities than non-feremented Rehmanniae Radix showing not only antioxidant effect but also cardiovascular protection.