The aim of this experiment was to find an antigen from Teladorsagia circumcincta to measure the level of IgA in ovine serum samples. Previous experiments used the titre of IgA to select sheep resistant to infection with T. circumcincta. By Western blotting 22 experimentally infected ewes recognized many proteins, but not all of them were recognized by all animals. Sheep were divided into two groups of animals: those that recognized a protein in Western blotting and those that did not. Among all proteins, three showed significant associations between protein recognition and the titre of IgA in the serum.