The process of betalains biosynthesis by Beta vulgaris L. hairy root culture in a temporary immersion system was studied. It was established that temporary immersion technique is suitable for the cultivation of hairy roots. The immersion frequency had significant effect on the biomass accumulation and the yields of betalains. The hairy root culture biosynthesized 18.8 mg g(-1) dry biomass (DB) betalains (9.6 mg g(-1) DB betacyanins and 9.2 mg g(-1) DB betaxanthins) at immersion frequency with 15 min flooding and 60 min stand-by periods. The maximal growth index (16.6) was achieved at 15 min flooding and 75 min stand-by periods. Data on the relationships in the biological system "Nutrient medium-B. vulgaris L. hairy root culture-Betalains" are presented. (c) 2005 Elsevier Ltd. All rights reserved.