The experiments were carried out to determine the optimum conditions for the induction of hairy roots in ginseng(Panax ginseng C.A. Meyer) by Agrobacterium spp. We were examined the antibiotics resistance of Agrobacterium spp and various ginseng parts, and the media for induction of hairy roots. The optimum concentration of NaOCl for sterilization of ginseng root segments without tissue damage with reduce of contamination was 7% NaOCl for 15-20 min and 9% NaOCl for 5 min, respectively. The more ginseng ages, the more contamination of ginseng root segment by sterilized in 7% NaOCl for 20 min, and especially in ginseng root segments with epidermis in six-year old roots. The growth of Agrobacterium spp were inhibited, but ginseng root segments was death in 30mg/L tetracycline. In 500mg/L cefotaxime or 500mg/L carbenicillin, the growth of Agrobacterium sup were inhibited, and root segments was grown normally. The optimum conditions for induction of hairy roots were using the root segments of three-year old ginseng cultured in 1/2MS medium supplemented with 500mg/L cefotaxime, and inoculation of Agrobacterium to root segments were better co-culture than smear method. After 2 weeks co-culture, the callus induced in cambium of root segments cultured in 1/2MS solid medium with 500mg/L cefotaxime. And then after 2 weeks, ginseng hairy roots were induced in callus of root segments. PCR analysis of rot C gene fragment confirmed that hairy roots were transgenic tissues.