In Poland, the most common pest slugs in agricultural crops are Arion vulgaris Moquin-Tandon, Deroceras reticulatum (O. F. Müller), and locally occurring Arion rufus (Linnaeus). They cause significant damage to winter oilseed rape and winter wheat. In recent years, they have also occurred in cultivations of various legume species (Fabaceae). However, information on the extent of damage caused by these species is still insufficient. To assess the extent of damage, young plants of common sainfoin, bird’s-foot trefoil, red clover, alfalfa, white melilot, and oilseed rape were exposed to grazing by the slug species investigated under laboratory conditions. It was found that oilseed rape plants were more susceptible to damage by the slugs studied compared to bird’s-foot trefoil plants. The susceptibility of the other plants studied varied depending on the slug species.