The weights and ginsenoside levels of twenty 4-year-old American ginseng (Panax quinquefolius) roots harvested from a homogeneous-looking 1-m2 plot were determined. It was found that the dry weight of the roots ranged from 3.5 to 22.8 g, a factor of 6.5; whereas the ginsenoside levels of these roots ranged from 24.7 to 56.4 μmol/g, a factor of 2.3. Further, it was found that the larger plants also contained higher ginsenoside levels on a weight basis. This finding is based, in part, on the ginsenosides in P. quinquefolius being located in both the periderm and cortex and the xylem and pith portions of the root. As the environmental variation experienced by the plants analyzed in this study was minimized, a portion of the variation found in these traits is likely to be a result of genetic diversity within the crop. These findings indicate that a cultivar of P. quinquefolius could be developed that would yield plants that have both an average weight and ginsenoside level per gram of tissue substantially greater than that of the existing crop. Keywords: Panax quinquefolius, American ginseng, ginsenosides, genetic selection.