The effects of agitation and aeration on the growth of carrot hairy roots were investigated. When hydrodynamic stress index was above 0.001 cm/s, the growth rate of hairy roots decreased sharply. When volumetric O-2 transfer coefficient was high, the specific growth rate was also high. However, the specific growth rate approached the maximum value when the volumetric O-2 transfer coefficient was over 4 h(-1). It is therefore necessary to maintain low hydrodynamic stress and high volumetric oxygen transfer for high density culture of hairy roots. By considering hydrodynamic stress and oxygen transfer, a never bioreactor type was suggested for hairy roots cultivation