The transformation of Torenia fournieri L. mediated by Agrobacterium rhizogenes was studied. Almost all roots induced by four bacterial strains,R1000, R1601, A4 and R1205 were putative hairy roots. The effects of bacterial strains, bacterial concentration, acetosyringone, silver nitrate and cocultivationpH on Torenia transformation were investigated. Strain R1000, co-cultivation for 3 days, 30Amol L_1 acetosyringone, 4mg L_1 silvernitrate and pH 6.5 in the cultivation medium provided the optimal conditions under which transformation frequency approached 90%.