In Broiler industry strict Vaccination schedule is followed throughout the world. It''s importance increases many folds in developing countries like Pakistan. Out of these, IBD (Infectious Bursal Disease/Gumboro Disease)vaccine and ND (Newcastle Disease) vaccine are considered the prime steps. It is documented fact that both of these vaccines also affect not only titres but have immunopathological effects as well. It is author''s M.Sc.(Hons.)Research project which he completed in the year 2002. This research work has also been published in Pakistan Veterinary Journal (PVJ)in the form of a Research paper in 2003. In this project it was proved that how three selected strains of IBD Vaccination cause immunopathological and immunosuppressive effects in Broiler.