Adventitious roots of Panax ginseng C.A. Meyer (a natural tetraploid) were treated with 50 or 100 mg L-1 colchicine for 12, 24, 36, 48, or 60 h to induce polyploid (octoploid) roots. The largest number of octoploid roots was obtained with a 100 mg L-1 colchicine treatment over 60 h. To verify that ginsenoside was being accumulated in the developing tissues, the tetraploid (control) and octoploid roots were cultured for 40 d in Murashige and Skoog media that lacked NH4NO3 but was supplemented with 2 mg L-1 naphthaleneacetic acid and 50 g L-1 sucrose. Levels of fresh and dry biomass were greater in the octoploid roots. Although total ginsenoside and Rb-group ginsenoside contents were less in the octoploid roots than in the tetraploids, the former had a higher amount of Rg-group ginsenosides (especially Rg1). These results demonstrate the benefit that polyploid adventitious roots provide in enhancing the production of secondary metabolites in ginseng.