The objectives of these investigations are: - to determine the efficacy of homologous vaccine based on AI H5N1 strain recently isolated in Egypt and heterologous inactivated (H5N2- Intervet) in SPF-Chicks and the role of the maternal antibodie in the protection. Inaddition the role. - The role of the maternal antibodies in protection of broiler chicks and the efficacy of one caccination shot in protection against H5N1 collection and virus shedding.