Essential oils (EOs), being mixtures of various natural compounds, constitute anattractive source of novel antimicrobial agents. Along with multiple studies concerningtheir rich biological activity, there are different methods allowing to determine bothantimicrobial activity in direct contact, as well as through the activity of vapours. Thymeconstitutes one of the most common aromatic herbs used for pharmaceutical, cosmeticand culinary purposes. The aim of the study was to compare the antibacterial activity ofliquid and vapour phases of Thymus vulgaris L. essential oil (TEO) against most commonpathogenic Gram-positive ( Staphylococcus aureus ATCC 25913, Enterococcus faecalisATCC 29212, Bacillus cereus ATCC 10876) and Gram-negative (Escherichia coli ATCC25922, Salmonella typhimurium ATCC 14028, Pseudomonas aeruginosa ATCC 27853)microorganisms. To determine TEO antibacterial properties, two methods were used:disc-diffusion assay so as to test activity in direct contact; disc-volatilization assay so as todetermine activity in gaseous contact.Statistical analysis showed that Gram-positive bacteria were more sensitive to TEOvapours than Gram-negative (p=0.005), while in the case of disc-diffusion assay, no suchdifferences were evident. Moreover, sensitivity towards TEO differed among Gram-positive bacteria in disc-diffusion (p=0.009) and discolatilization assay (p=0.001).Among Gram-negative rods, a statistically higher sensitivity regarding E. coli was notedwhen compared to S. typhimurium in both direct (p=0.011) and gaseous (p=0.006) TEOcontact. No activity of TEO against P. aeruginosa was found.As thyme essential oil exhibited significant antimicrobial activity against Gram-positivebacteria in gaseous contact, this justifies its use as an addition to inhalation agents toprevent or support the treatment of upper respiratory tract infections. Further studiesshould therefore apply other methods for determining the antibacterial activity of TEOvapours to assess the exact minimal concentration inhibiting bacterial growth.