Ginseng (Panax ginseng C.A. Meyer) hairy root transformed with Agrobacterium rhizogenes (strain A4) was examined cytogenetically and histologically to assess its characteristics. The optimum growth of hairy root obtained in hormone-free MS medium (sucrose 30 g/L, pH5-6) for long period cultures. All hairy root strains (HB1, HB2, HB3) had the 2n diploid number (2n=48) of chromosomes in root tip cells. There were no alteration in chromosome structure except in one cell of HB3 strain. Results of SDS-PAGE showed a few difference in pattern and number of bands between normal and hairy root of ginseng. The root anatomy of normal root and hairy root differed each other. The hairy root had a clearly defined vascular strand, and the morphology of cortical cells were disorganised with large intercellular spaces.