In recent years Arion subfuscus (Drap.) is increasingly often observed in agricultural crops. Its abundance and effect on winter oilseed rape crops were studied. Its abundance was found to be much lower than that of Deroceras reticulatum (O. F. Müll.). Preferences of A. subfuscus to oilseed rape and 19 other herbaceous plants were determined based on multiple choice tests in the laboratory. Indices of acceptance (A.I.), palatability (P.I.) and consumption (C.I.) were calculated for the studied plant species; accepted and not accepted plant species were identified. A. subfuscus was found to prefer seedlings of Brassica napus, while Chelidonium maius, Euphorbia helioscopia and Plantago lanceolata were not accepted.