The aim of this study was to obtain high-yielding cell cultures of Rubia cordifolia by applying gamma irradiation and subsequently scaling up for anthraquinone production in a bioreactor. Calli cultured on MS medium was irradiated at variable doses between 2 Gy and 30 Gy. The callus cultures that were irradiated at 8 Gy accumulated a maximum alizarin level of 26.86 mg g^-1 DW and a purpurin level of 44.85 mg g^-1 DW during the M₁T₄ (fourth sub-cultures after gamma irradiation treatment) subculture, which was 6-fold and 11-fold higher than those of the nonirradiated callus cultures, respectively. Suspension cultures that originated from high-yielding callus cultures irradiated at 8 Gy were scaled up in an 8-L stirred bioreactor equipped with different impellers. The callus cultures in a bioreactor using a helical ribbon for homogenous mixing synthesized 63.58 % more anthraquinones than  those in the bioreactor equipped with a Rushton disc turbine. This is the first report on the production of alizarin and purpurin in a bioreactor.