Callus cultures of Saussurea medusa were cultivated on solid culture medium supplemented with either Ce3+, La3+,Nd3+ or a mixture of rare earth elements. Ce3+, 0.05 mM, gave the highest biomass (0.53 g dry wt per flask) and total flavonoids (27.5 mg per flask), which were, 70% and 100% higher than those without Ce3+ addition, respectively. Ce3+, 0.01-0.1 mM, or La3+, 0.05 mM, or the mixture of rare earth elements, 0.025-0.1 mM, can substitute for 6-benzyladenine, and 0. 025 mM Ce3+ can partly substitute for naphthaleneacetic acid in promoting cell growth and biosynthesis of total flavonoids in S. medusa.