The outbreak of avian influenza virus (AIV) has spread in almost all provinces in Indonesia. Recently, it is reported, that layer chickens look healthy have decreased egg production. At necropsy, anatomical pathological lesions, such as pulmonary petechial and/or linear hemorrhages were observed. In chickens, AIV is endotheliotrophic, therefore a research needs to be done to evaluate whether the typical pulmonary hemorrhagic lesions is an AIV pathognomonic pathological lesions that can be used as a confirmative diagnosis for rapid and accurate AIV diagnosis. Twenty layer chickens looked healthy were used. All were necropsied and observed anatomical pathological lesions in the lungs. The lungs were then made histopathologically with routine staining of hematoxylin and eosin. The pulmonary anatomical pathological and histopathological lesions due to AIV infection were confirmed by applying immunohistopathological streptavidin biotin (IHC SB) with polyclonal antibody anti AIV nucleotrotein. The paraffin blocks of the lungs that are AIV immuniopathological positive were recut and stained with a routine hematoxylin and eosin stain. Histopathological lesion(s) of the hemorrhagic lungs were examined under the microscope, and were analyzed descriptively. In the present study, all layer chickens which were necropsied, had anatomical pathological lesions of petechial and / or linear hemorrhages and histopathological lesions of congestion and severe, diffuse hemorrhages in the lungs. It was concluded that pathological lesions in the lungs are pathognomonic in chickens infected with AIV