Abstract :The aim of this study was to evaluate the bactericidal and fungicidal activity of the commercial mouthwash containing 0.147% v/v of LAE against potentially pathogenic microorganisms of the oral cavity, in relation to the exposure time. Studies were conducted with the use of standard strains of microorganisms (Streptococcus oralis ATCC 6249, Staphylococcus aureus ATCC 25923, ATCC 33384 Aggregatibacter actinomycetemcomitans, Candida albicans ATCC 10231), the suspension was contacted with 4 ml of mouthwash containing 0,147% v/v LAE or 18% ethanol or 0, 2% chlorhexidine solution. After 5, 10, 20, 30 and 60 min of incubation periods of each test sample and the control samples at the room temperature, a volume of 20 µl was placed on a Columbia agar base with 5% sheep blood (bacteria) or Sabouraud agar (fungi). After 24 hrs or 48 hrs of incubation at 37°C (bacteria) or 35°C (fungi), the grown colonies of microorganisms were counted using an "aCOLyte" colony counter (Symbios, Cambridge, UK). The total reduction in the growth of all tested strains of reference microorganisms was already visible after 5 min of incubation with mouthwash containing 0,147% v/v LAE and 0.2% chlorhexidine solution, while the incubation with 18% ethanol did not show such an effect even after 60 min.