abstract the composition of the essential oil of the aerial parts of artemisia lobelii during four stages of the growing cycle (full foliation stage, pre-bloom, full bloom and post-bloom stage; between june and october) were studied by gc/ms. the major constituents of the oil were camphor (33.2-36.8%), 1,8-cineole (15.2-21.1%) and artemisia ketone (6.0-24.2%). the antimicrobial activity of oil against escherichia coli, klebsiella pneumoniae, pseudomonas aeruginosa and staphylococcus aureus was investigated. it was found that the oil showed strong activity against pseudomonas aeruginosa.