The composition of the leaf essential oils of 13 taxa of the smooth leaf margin Juniperus in sect. Sabina from the western hemisphere are reported and compared. In addition, DNA fingerprinting revealed similar patterns among these species. Based on these data, a new species, very similar to J. blancoi and J. scopulorum, is recognized from northern Mexico: Juniperus mucronata sp. nov. R.P. Adams. Although the terpenes and morphology support the recognition of J. barbadensis var. lucayana (see Adams, R.P., 1995a, Revisionary study of Caribbean species of Juniperus (Cupressaceae). Phytologia, 78, 134-150), the RAPDs do not favor that alignment. Therefore, J. lucayana will be recognized as a distinct species at present. The recognition of J. ekmanii and J. urbaniana as varieties of J. gracilor is supported by the RAPDs data and these varieties will be maintained in the treatment of Juniperus.