The essential oils from the flower, leaf, stem and root of Nepeta persica Boiss., analyzed by GC and GC/MS, were shown to contain 4abeta,7alpha,7abeta-nepetalactone (58.5%, 62.3%, 66.2% and 27.1%, respectively), and 4aalpha,7alpha,7abeta-nepetalactone (33.0%, 28.3%, 24.9% and 7.6%, respectively). The other main component of the flower and stem oils was alpha-pinene (3.6% and 4.4%) and of the leaf oil beta-ocimene (3.6%). In the root oil, other main constituents were alpha-pinene (40.4%), alpha-amorphene (5.3%), gamma-cadinene (2.9%), and cis-calamenene (2.5%). Nepetalactone was the major component of the flower, leaf and stem oils, which are thus important sources of nepetalactone. Antibacterial activities of the flower, leaf, stem and root oils were evaluated using the micro-dilution broth method. Inhibitory effects on Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Enterococcus faecalis were recorded. The flower, leaf, stem, and root oils had difference activities against the test microorganisms. The antibacterial property of the essential oils might be ascribed to their high content of nepetalactone isomers.