The soluble protein profiles of unsporulated oocysts among the three geographical strains of Eimeria maxima were compared by SDS-PAGE(sodium dodecyl sulfate-polyacrylamide gel)electrophoresis technique. The results showed that the band profile from each of the strains were similar, although there were different in the immunogenicity of the three Eimeria maxima to some degree. There were at least eight protein bands in unsporulated oocyst, including two distinct proteins with 42 000 and 39 000, three relative distinct proteins with 36 000, 26 000, 22 900, and less-distinct proteins with 109 800, 86 900 and 62 800. The result indicated that SDS-PAGE electrophoresis could not detect the differences of the soluble protein profiles of unsporulated oocysts in the three different immunogenic strains of Eimeria maxima.