Abstract
Monovalent and Bivalent formalin inactivated vaccine was prepared using two different in pathogenecity local isolates of adeno virus serotype 4 which causing hydropericardium hepatitis syndrome in chicken The efficacy evaluation was carried out by S/C injection of prepared vaccine in 10 days old chickens . Antibodies titer was calculated after 1 and 2 weeks post injection , challenge test after two weeks of injection was performed by the virulent isolates separately and compared with imported monovalent vaccine as positive control . Results showed that the bivalent prepared vaccine was more efficient than monovalent and imported vaccine.