The aim of this work was to explore antimicrobial activity of the essential oils from three species of genus Acinos (Lamiacea family): A. arvensis, A. hungaricus and A. alpinus (two different localities).

The plant material was collected in full blossom phase, A. arvensis at the locality Rtanj (1998), A. hungaricus in the locality of Kurvin grad-Seličevica (1999), A. alpinus in the locality of Prevalac-Šara (1997) and A. alpinus at the locality Sićevo gorge (1999). The essential oils were isolated by hydro-distillation of dried herb material, in a Clevenger type apparatus (Ph. Jug. IV).

By diffusion method on the disk (Ph. Jug. IV), the antimicrobial activity of the essential oils (in the dilution of 1:20 with ethanol) has been investigated through the application of the followingmicro-organisms: Escherichia coli 95 TORLAK, Klebsiella pneumoniae ATCC 10031, Pseudomonas aeruginosa ATCC 9027 and Staphylococcus aureus ATCC 6538.

The antimicrobial activity of the oil from A. arvensis on the microorganisms decreases in the following order: Klebsiella pneumoniae, Staphylococcus aureus, Escherichia coli. The activity of the oil from A. alpinus (both localities) on the microorganism's decrease in the next order: Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, while the oil obtained from A. hungaricus affects only the Escherichia coli. Pseudomonas aeruginosa is resistant to essential oils from all mentioned species of genus Acinos.

Key words: antimicrobial activity, essential oil, Acinos arvensis, Acinos hungaricus, Acinos alpinus, Lamiaceae.