Theileria lestoquardi is the causative agent of malignant theileriosis of sheep and goats, causing morbidity and mortality in these animals worldwide. Western blot analysis based on T. lestoquardi schizont antigens was carried out using sera collected from Iranian sheep, which had been immunized with T. lestoquardi schizont-infected cells. The results of Western blot analysis demonstrated that schizont-immunized animals produced antibodies reacting with protein bands at 73, 42, 20, 14, and 12 kDa. Comparison of the results of the current Western blotting test with earlier studies of Theileria spp. revealed two immunogenic schizont proteins with molecular weights of 73 and 42 kDa shared between T. annulata and T. lestoquardi. Two other proteins with molecular weights of 14 and 12 kDa have not been previously found in other Theileria species. Our results suggest that the 73-kDa protein could be a potential vaccine candidate and that the 14- and 12-kDa proteins could be considered as diagnostic antigens.