2, 4-Disubstituted quinolines with additional substituents in positions 5–8 have been found to have anthelmintic properties. A number of 2, 4-dimethoxy-6-or 8-arylquinolines have potent activity against the sheep nematode Haemonchus contortus, with LD99 values of the same order of magnitude as levamisole. These arylquinolines maintain their activity against levamisole-, ivermectin-and thiabendazole-resistant strains of H. contortus.