A suspension culture of Thalictrum minus L. synthesizes a quaternary isoquinoline alkaloid berberine, which is used for stomach and gall bladder medication. By HPLC technique, protoberberine alkaloids of a T. minus cell culture were shown to comprise 75-85% of berberine, 7-15% of palmatine, and several minor alkaloids. The culture was characterized by the release of 70-80% of alkaloids into the nutrient medium. Chlorides (50-60 mM) enhanced berberine synthesis. In the Murashige and Skoog medium containing NH4Cl, KCl or NaCl, the alkaloid production was increased to 440, 370, and 290 mg/l, respectively, vs. 180 mg/l in the control culture. Chlorides did not inhibit culture growth. At the steady-state phase, the content of alkaloids was equal to only 0.73-0.87% of cell dry weight, whereas the total alkaloid amount, taking into account their release into the medium, was 6% against 2.5% in the control suspension. Along with alkaloids, the culture synthesized substantial amounts of phenolic compounds (7-9%), but 80-86% of the latter remained in the cells.