The impact of conditioned medium addition on cell growth and production of ginseng polysaccharide by Panax notoginseng cells was investigated in 1 1 concentric-tube airlift bioreactors. The maximum dry cell weight (DW) for a conventional cell culture in MS medium was 12.24 +/- 0.60 g l(-1) at day 15 with an average growth rate of 0.156 +/- 0.011 day (1). In the cell cultures with addition of 50%. (by volume) conditioned medium, a cell density (by dry weight) of 13.50 +/- 2.81 g l(-1) at day 14 and an average growth rate of 0.192 +/- 0.055 day (-1) were obtained. The maximum DW obtained in a high-density culture was 22.55 +/- 4.78 g l(-1) on day 17 with an average growth rate of 0.231 +/- 0.061 day (- 1), and 24.12 +/- 1.85 g l(-1) on the same day with an average growth rate of 0.251 +/- 0.024 day -(1) in the high-density culture with conditioned medium. The production and productivity of ginseng polysaccharide in the conventional culture was 1.23 +/- 0.16 g l(-1) (on day 16) and 49.2 +/- 13.1 mg l(-1) day(-1), respectively, and a much higher production titre of 3.12 +/- 0.37 g l(-1) (day 17) and a productivity of 151.8 +/- 25.6 mg l(-1) day-' were achieved in high-density cell culture with addition of conditioned medium. Addition of conditioned medium effectively enhanced cell growth and accumulation of ginseng polysaccharide in both conventional and high-density cell cultures in the airlift bioreactors.