Abstract:Hairy roots of Trichosanthes kirilowii Maxim. were successfully induced by infection with Agrobacterium rhizogenes strain R1601 and an in vitro culture system of thehairy roots was established. The presence of trichosanthin in the hairy roots of T. kirilowii was confirmed by western blotting. The yield of trichosanthin was determined to be 8. 16 mg/g fr. wt with SDS-PAGE gel electrophoresis and thin layer chromatography.