The contents of five ginsenosides (Rg1, Re, Rb1, Rc and Rd) were measured in American ginseng roots collected from 10 populations grown in Maryland. Ginsenoside contents and compositions varied significantly among populations and protopanaxatriol (Rg1 and Re) ginsenosides were inversely correlated within root samples and among populations. The most abundant ginsenoside within a root and by population was either Rg1 or Re, followed by Rb1. Ginseng populations surveyed grouped into two chemotypes based on the relative compositions of Rg1 and Re. Four populations, including the control population in which plants were grown from TN and WI seed sources, contained roots with the recognized chemotype for American ginseng of low Rg1 composition relative to Re. The remaining 6 populations possessed roots with a distinctive chemotype of high relative Rg1 to Re compositions. Chemotype did not vary by production type (wild versus cultivated) and roots within a population rarely exhibited chemotypes different from the overall population chemotype. These results provide support for recent evidence that relative Rg1 to Re ginsenoside contents in American ginseng roots vary by region and that these differences are likely influenced more by genotype than environmental factors. Because the physiological and medicinal effects of different ginsenosides differ and can even be oppositional, our findings indicate the need for fingerprinting ginseng samples for regulation and recommended usage. Also, the High Rg1/Low Re chemotype discovered in MD could potentially be used therapeutically for coronary health based on recent evidence of the positive effects of Rg1 on vascular growth.