Аннотация:The aim of the research was to study the effect of volatile organic compounds (VOCs) of various types, secreted by microorganisms (ketones, alcohols, terpenes, dimethyl disulfide (DMDS)), on the planktonic growth and formation of the Gram-negative marine bacterium Vibrio harveyi BB120 biofilms. This pathogen bacterial species causes infectious diseases of various marine organisms (vertebrates and invertebrates), which hinders the development of marine aquaculture. Materials and methods. The cells were grown on 96-well polystyrene plates with light shaking. The planktonic growth was determined by optical density. The level of formed biofilm was determined by staining them with crystal violet with subsequent ethanol extraction. The level of biofilm formation was estimated by the color intensity of the solution. Results. It was demonstrated that the effect of all studied VOCs led to a decrease of the planktonic growth of V. harveyi BB120. (–)-Limonene, β-ionone, and (+)-α-pinene had the strongest effect on bacteria; 2-phenylethanol had a slightly weaker effect. The level of biofilms (as a percentage of the control without VOC) in all cases was higher when exposed to the indicated VOC than the level of planktonic growth of V. harveyi BB120, which indicates a higher resistance of the cells in biofilms to VOC. The patterns of the effect of various VOCs on the biofilm formation in the studied VOC ranges were different. With an increase in the amount of the added 2-pentanone and DMDS, an increase in biofilm formation was observed; the addition of (–)-limonene, 2-phenylethanol, isoamyl alcohol, and (+)-α-pinene to the culture led to a decrease in the level of biofilms. Conclusions. The inhibitory effect of VOCs with different structures (2-pentanone, β-ionone, isoamyl alcohol, 2‑phenylethanol, (–)-limonene, (+)-α-pinene, dimethyl disulfide) on the growth of V. harveyi BB120 was for the first time demonstrated. These data are of interest for the control of infections caused by V. harveyi and other pathogenic representatives of the genus Vibrio.