AbstractThe antibacterial activity of the essential oil of Abies balsamea (balsam fir) was evaluated against Escherichia coli and Staphylococcus aureus. The essential oil of A. balsamea was found to be inactive against E. coli (>100 µg/mL) and active against S. aureus, with an MIC of 56 µg/mL. The oil composition was analysed by GC‐MS and the antibacterial activity of each oil constituent was determined. The essential oil of A. balsamea is essentially constituted of monoterpenes (>96%) and some sesquiterpenes. β‐pinene (29.9%), δ‐3‐carene (19.6%) and α‐pinene (14.6%) were the major components. β‐pinene and δ‐3‐carene were found inactive against both bacteria strains. However, three constituents of the essential oil were active against S. aureus: α‐pinene, β‐caryophyllene (0.4%) and α‐humulene (0.2%) with MIC values of 13.6 µg/mL, 5.1 µg/mL and 2.6 µg/mL, respectively. Copyright © 2006 John Wiley & Sons, Ltd.