Background: Transgenic plant suspension cultures could be used as an effective tool for the biotransformation of exogenous compounds. Objective: To investigate the biotransformation of furannoligularenone ( 1 ) by transgenic crown galls of Panax quinquefolium. Materials and Methods: Compound 1 was administered into the crown gall cultures and co-cultured for 6 days. The cultures were dried and extracted with methanol for HPLC analyses. The extract was separated on column chromatography, and biotransformation products' structures were elucidated by the physicochemical properties and the data of NMR and MS. Moreover, three flasks were randomly chosen each day to establish time-course during the period for co-culturing . Results: Co-culturing compound 1 with crown galls yielded two compounds, 3-oxo-eremophila-1,7(11)-dien-12,8-olide ( 2 ) and 3-oxo-8-hydroxy-eremophila-1,7(11)-dien-12,8-olide ( 3 ), which were obtained by biotransformation using P. quinquefolium crown galls for the first time. Time-course investigation revealed that the mole conversion ratio reached the highest level of 45.5% and 33.9% on fourth and fifth day after substrate administration, respectively. Furthermore, a proposal biosynthesis pathway was given from compound 1 to compounds 2 and 3 . Conclusion: This was the first example of compound 1 being successfully converted into compounds 2 and 3 by transgenic crown galls of P. quinquefolium.