We investigated the effects of different concentrations of auxin and auxin/cytokinin combinations, inoculum sizes and Murashige and Skoog (MS) medium dilutions on biomass and accumulation of total phenols and flavonoids in adventitious roots of Hypericum perforatum. The optimized conditions for the shake flask culture growth and secondary metabolites production were 0.1 mg/l kinetin with 1 mg/l indole-3-butyric acid (IBA), an inoculum density of 6 g/l fresh weight (FW) and 1/2MS in the 5-week old cultures. By inoculating 6 g/l of adventitious roots into a 3-1 balloon type bubble bioreactor (BTBB) containing 1/2 MS medium supplemented with 0.1 mg/l kinetin with 1 mg/l IBA, 104.2 g/l adventitious roots were harvested containing 56.47 +/- 0.22 mg/g dry weight (DW) total phenolics, 35.01 +/- 1.26 mg/g DW flavonoids, 0.97 +/- 0.06 mg/g DW chlorogenic acid and 1.389 +/- 0.80 mg/g DW hypericin. The results of our study contribute to optimization and development of bioreactor technology for adventitious root cultures of H. perforatum for the production of hypericin. (C) 2010 Elsevier Ltd. All rights reserved.