The objective of this study was to evaluate variations in leaf essential oil (EO) content and composition of Juniperus species in the Bighorn Mountains {J comimunis L. (common juniper), J. horizontalis Moench. (creeping juniper), and J scopulorum Sarg. (Rocky Mountain juniper)} in Wyoming, USA. The EO was extracted via steam distillation of fresh leaves (needles). The EO composition of the three Juniper species varied widely. Overall, the essential oil content of fresh leaves was 1.0% (0.4-1.8% range in different accessions) in J. communis, 1.3% (1.2 to 1.6% range) in J. horizontalis, and 1.1% (0.7-1.5% range) in J. scopulorln. The EO chemical profile of J. communis was very different from that of the other two species. The concentration of α-pinene in the oil was 67- 80% in J. communis, 2.8-6% in J. horizontalis, and 2.3-13% in J. scopulorun. The concentration of sabinene was 57-61% of the oil of J. horizontalis and 13- 59%. in oil of J. scopulorum, whereas sabinene was either below 1% or not detected in J. communis. The oils of J scopulorm and J horizontalis had higher antioxidant capacity than that of J. communis. The oils of the three junipers did not show significant antimicrobial activity against 10 organisms. The diversity of the essential oil composition of these three junipers may encourage diverse industrial applications of Juniperus leaf essential oil.