We report an efficient, simple, and cost-effective protocol for the isolation of genomic DNA from an aromatic medicinal plant, common sage (Salvia officinalis L.). Our modification of the standard CTAB protocol includes two polyphenol adsorbents (PVP 10 and activated charcoal), high NaCl concentrations (4 M) for removing polysaccharides, and repeated Sevag treatment to remove proteins and other carbohydrate contaminants. The mean DNA yield obtained with our Protocol 2 was 330.6 μg DNA g(-1) of dry leaf tissue, and the absorbance ratios 260/280 and 260/230 nm averaged 1.909 and 1.894, respectively, revealing lack of contamination. PCR amplifications of one nuclear (26S rDNA) and one chloroplast (rps16-trnK) locus indicated that our DNA isolation protocol may be used in common sage and other aromatic and medicinal plants containing essential oil for molecular biologic and biotechnological studies and for population genetics, phylogeographic, and conservation surveys in which nuclear or chloroplast genomes would be studied in large numbers of individuals.