abstract hydrodistilled volatile oils from the aerial parts of artemisia afra and leaves of leonotis ocymifolia var. raineriana were investigated, by a combination of gc and gc/ms. from a. afra 37 compounds were identified, representing 95.3% (area percent) of the total oil and from l. ocymifolia var. raineriana, 27 compounds were identified, representing 91.1% of the total oil. among the identified components camphor (46.2%), -thujone (15.2%), artemisia ketone (7.4%) and 1,8-cineole (4.2%) were found as the main components of a. afra oil and germacrene d (36.8%), (z)--ocimene (7.9%), -caryophyllene (7.0%) and (e)--ocimene (4.4%) were the major components of l. ocymifolia oil. furthermore, the oils, as well as nine of their constituents, were evaluated for their antimicrobial activity, against six bacteria, two oral pathogens and three pathogenic fungi. the results showed that the oil of a. afra has a moderate antimicrobial activity, while the oil of l. ocymifolia exhibited a stronger one against gram-negative bacteria and oral pathogens, and a weaker one against gram-positive bacteria. this interesting profle can be attributed to the high content of the oil, of germacrene d which is known for its antimicrobial activity.