Fowl cholera (FC) and Avian Influenza (AI) are two of the major economically important respiratory and septicaemic disease of poultry in Egypt and allover the world. A field trails was conducted to evaluate the immunogenicity of an experimentally multivalent inactivated Fowl cholera (P. multocida) and Avian Influenza (H9N2) vaccine. The In this study a combined inactivated Montanide ISA fowl cholera and AI vaccine was prepared then the immunization potency and protective efficacy were evaluated through experimental application on different poultry breeds including broiler breeder, broiler and turkey flocks.The peak of humeral immune response against P. multocida as measured by ELISA was at the 5th week post vaccination and at 3rd week post boostering all over the used poultry flocks. At the same time, AI immune response as measured by HI reached the peak at the 6 th week post vaccination and at 2 nd week post boostering. Regarding the challenge test, the protection levels were 76.6, 70 and 80% and 90, 86.6 and 93.3% against P. multocida while protection levels were 83.3, 80 and 86.6% and 93.3, 90 and 96.6% against AI virus after challenge with the used virulent strains post single and booster dose respectively. In conclusion the combined prepared fowl cholera and AI vaccine succeeded in eliciting protective antibody titres and full protection against both fowl cholera and AI diseases.