Technical Abstract: The objective of this study was to evaluate variations in podophyllotoxin concentrations in Juniperus species found in the Big Horn Mountains in Wyoming. It was found that Juniperus species in the Big Horn Mountains included three species; J. communis L. (common juniper), J. horizontalis Moench. (creeping juniper) and J. scopulorum Sarg. (Rocky Mountain juniper). Of these species, none of the 36 accessions of J. communis contained detectable amounts of podophyllotoxin. All accessions of J. scopulorum but one contained podophyllotoxin. Podophyllotoxin concentration in J. horizontalis and J. scopulorum did not correlate to the elevation of the selection sites. The concentration of podophyllotoxin in J. scopulorum ranged from 0 to 0.40 %, while the concentration of podophyllotoxin in in J. horizontalis ranged from 0.27 to 0.73 %. Overall, J. horizontalis accessions in the Big Horn Mountains showed higher concentration of podophyllotoxin than the one in J. scopulorum. The range of concentrations in podophyllotoxin in J. horizontalis and J. scopulorum in the Big Horn Mountains were within the range or (in case of J. horizontalis), much higher than the ones reported previously for J. virginiana. This is the first report on podophyllotoxin in J. horizontalis. The concentrations of podophyllotoxin in some accessions of J. horizontalis were twice as high as the ones reported previously for any other Junipers. This study demonstrated that Juniperus species in the Big Horn Mountains have a potential to be used as a source for podophyllotoxin.