AbstractIn this study the antimicrobial activities of five volatiles, which represent main compounds of several essential oils, were tested. Terpineol, (R)‐(–)‐linalool, carvacrol, (S)‐(–)‐perillaldehyde and 1,8‐cineole were evaluated for their influence on airborne microbes when vaporized with a room diffuser. In the present investigation terpineol and (S)‐(–)‐perillaldehyde showed the highest antimicrobial activities. The average reduction of the germ count was 59.4% and 42.3%, respectively, after 5 h of spreading in a testing room. Carvacrol (average germ reduction 37.5%) and (R)‐(–)‐linalool (29.7%) showed lower results. For 1,8‐cineole only, no unambiguous antimicrobial effect was detectable. It has to be considered that the amounts of vapour spread during 5 h of testing time were different, depending on the volatility of the scent used. Nevertheless, four of the investigated volatiles showed satisfying antimicrobial action against airborne microbes. Copyright © 2008 John Wiley & Sons, Ltd.