This study carried out to assess and characterize the immunogenicity of subcutaneously administered oocyst protein of wild strain E. maxima in inducing protective immunity against virulent E. maxima infection in chickens. Twenty-four broilers one day old was divided into 2 groups, each group consisted of twelve heads. Group 1 as the control group was given subcutaneously to the neck with two doses: the first dose was given at 4 days of age with Freund's Complete Adjuvant emulsified in PBS and a booster dose was given at 18 days of age with Freund's Incomplete Adjuvant emulsified in PBS. Group 2 was given subcutaneously to the neck in two doses: the first dose was given at 4 days of age with 50 μg of E. maxima oocyst protein emulsified in Freund's Complete Adjuvant and a booster dose was given at 18 days of age with 50 μg of oocyst protein emulsified in Freund's Incomplete Adjuvant. After 14 days of booster, both groups were orally challenged 1 x 104 virulent E. maxima. The assessment and characterization of oocyst protein immunogenicity of wild strain E. maxima in inducing protective immunity to infection of E. maxima virulent in chickens evaluated the development histomorphologically of E. maxima in intestine and oocyst production examination. Chickens given E. maxima oocyst protein were challenged at 32 days of age, indicating that histomorphologically endogenous development of the parasite in the intestines appeared to have decreased proliferation and suppressed the rate of oocyst production by about 72% compared to chickens that were not fed. Impaired development of endogenous parasites occurs due to protective immunity due to exposure to antigens so that the ability to reproduce and multiply parasites decreases. The results showed that protection against coccidia was relatively sufficient with the use of E. maxima oocyst protein as an ingredient for intestinal coccidiosis vaccine in broilers after being challenged. Eimeria maxima oocyst protein can generate protective immunity against homologous challenge through reduced parasite proliferation and the presence of parasitic defects.