Abstract: Molluscs, in Europe mainly slugs, are serious pests of many crops and ornamentals. The most harmful species are members of Deroceras and Arion genera. Currently, there are two ways of their control: chemical and biological. Conventional baiting pellets are based on methiocarb (banned in EU), metaldehyde (banned or will be banned soon in most of EU countries) or iron phosphate while biological methods are based on the nematode Phasmarhabditis hermaphrodita in combination with Moraxella osloensis bacterium. Among other, often limited methods such as salt, beer traps, slug bots etc., one could have a potential to become a new effective approach. Entomopathogenic nematodes of the genus Steinernema live in symbiotic association with bacteria of the genus Xenorhabdus. Bacterial symbiont is not able to live and infect insect without its nematode vector that transport bacteria directly to the new suitable host. On the other hand, nematode developing inside the cadaver needs protection for several days to finish the life cycle. This protection is possible thanks to the ability of bacteria to produce wide range of different metabolites that act e. g. as antibiotics, bactericides, fungistatics, repellents or antifeedants etc. Using of bacteria and their secondary metabolites in biological pest control is recently quite popular and seems to bring very promising results. Even the metabolites produced by bacteria Xenorhabdus spp. are known to be effective against some plant fungal pathogens, insects, protozoans and nematodes. In this contribution we would like to show how these metabolites can influence behaviour of slugs.