Newcastle Disease Virus (NDV) is a highly contagious pathogen and causes massive death rates in poultry. Our understanding of the free radicals pathophysiology of NDV is limited. To fill this gap, we present the findings of investigation on the pathological effect of NDV on vital organs of the chicken (Brain and liver). This books is divided into four chapters and it documents the 1) significant perturbations in the antioxidant defense system of the brain and liver of chicken during NDV infection 2) free radicals mediated immunopathological consequences which were gratified by the immunofluorescence studies 3) lower endogenous levels of vitamin E in the NDV infected animals. This book also describes the possible external supplementation of vitamin E to the infected birds for the improved antioxidant defense system, reduced viral titer, and improved life span of infected birds following pronounced immunity.