Egg-adapted gametocytes of Eimeria (E.) tenella (local isolates) were subjected to sodium dodecyl sulphate polyacrylimide gel electrophoresis under reducing conditions to fractionate the proteins. Immunogenicity of the gametocytes was detected by modified counter immunoelectrophoresis (MCIE) using convalescent sera from the outbreak cases of coccidiosis. Gametocytes of all the three isolates of E. tenella showed similar protein bands of molecular weights of 48.43, 27.20, 25.75, 22.57, and 12.92 kDa. MCIE recognized three precipitation bands with convalescent sera in comparison with the control. Results suggested that some of the 48.43-, 27.20-, 25.75-, 22.57-, and 12.92-kDa antigen(s) exist as soluble proteins in the parasite, which gave protection in our previous experiments against coccidiosis. Further studies on the biochemical characterization of the egg-adapted gametocyte antigen(s) and its role in E. tenella oocyst wall formation is underway.