Seventy five broiler chicks were used to determine the immunization of in ovo inoculation or intramusclular (I/M) injection of sonicatedoocyts (SO) antigen against E. tenella manifestation. The chicks were divided in to 3 equal groups compromising of 25 chicks each. The 1st group inoculated in ovowithSO of E. tenella and repeated by I/M injection at 21 days old. The 2nd group injected I/M withSO at day old and repeated at 21 days old, The birds of the 3rd group remains as control. All birds were challenge by 50,000 sporulatedoocysts of E. tenellaat day 28. No significant (P > 0.05) group difference was detected between the immunized and non-immunized groups for mean, WBC count, H/L ratio, lesion score, mortality and oocysts shedding until E. tenella challenge at day 28. After challenge test the in ovo and I/M immunized groups showed a great protective immunity against E. tenellainfection documented by significantly (P < 0.05) reduced mortality, lesion score and decreased fecal oocyst shedding, compared with non-immunized group. It is concluded that in ovo and I/M immuinzation of sonicatedoocyst stimulates a remarkable protection in broilers following E. tenellainfectioncomparing with non-immunized groups. There was no significance difference between the two procedures of immunization
