Paclitaxel is produced by various species of yew trees and hasbeen extensively used to treat tumors. In our research, ataxadiene synthase (TS) gene from Taxus brevifolia was used totransform the roots of cultured ginseng (Panax ginseng C.A.Meyer) to produce taxadiene, the unique skeletal precursor totaxol. The TS gene was successfully introduced into theginseng genome, and the de novo formation of taxadiene wasidentified by mass spectroscopy profiling. Without any changein phenotypes or growth difference in a TS-transgenic ginsengline, the transgenic TSS3-2 line accumulated 9.1 μg taxadieneper gram of dry weight. In response to the treatment of methyljasmonate for 3 or 6 days, the accumulation was 14.6 and15.9 μg per g of dry weight, respectively. This is the first reportof the production of taxadiene by engineering ginseng rootswith a taxadiene synthase gene.