The effects of light irradiation on growth and production of artermisinin were studied in hairy root cultures of Artemisia annua L. When the hairy roots were cultured under illumination at 3000 Lux for 16 h using several cool-white fluorescent lamps, and then darkness for 8 h, the dry weight and artemisinin concentration reached 13.8 g/l and 244.5 mg/l, respectively. The results obtained showed that the growth and artemisinin accumulation increased on improving the conditions of light irradiation, which affected metabolite formation conspicuously. Under optimal conditions, kinetics of growth, artemisinin accumulation and nutrient uptake were studied. (C) 2002 Elsevier Science Ltd. All rights reserved.