The wild boar is one of Europe's most popular game species and its densities are increasing. Management tools such as farm breeding, supplementary feeding, and translocations are more frequently employed and anthelmintics are increasingly used in game farms and translocations. Here, we report the results of a controlled slaughter study on the efficacy of an in-feed preparation of ivermectin in European wild boars naturally infected with various helminths. The efficacy of ivermectin against adult stages of Metastrongylus sp., Ascaris suum, Ascarops strongylina, Physocephalus sexalatus, and Simondsia paradoxa was 100%. Its efficacy against Oesophagostomum dentatum was 85.1%. There was no sufficient effect on Globocephalus urosubulatus, Trichuris suis, and Capillaria garfiai. The egg reduction in the treated group ( n=12) was 100% 6 days after the treatment. The importance of parasite surveillance and the application of anthelmintic treatments to wild boars in game farms or during translocations are discussed. We conclude that any attempt at helminth treatment in wild boars should consider the addition of a second compound with a more consistent effect on trichurids and other helminths.