A total of 25 commercial layer carcases from seven poultry farms in Morogoro municipality were examined for gross and histopathological changes. Grossly, splenomegally, renomegally and hepatomegally were striking features. Both the liver and spleen were almost twice the size of normal organs. The surfaces of the liver, spleen, kidneys, lungs and the heart had yellowish white to grey multifocal and focally extensive patches of variable sizes. The lungs were consolidated. Histologically, the liver, spleen, kidneys, lungs, and the heart had heavy infiltration of large lymphocytes with abundant cytoplasm and poorly stained eosinophilic cytoplasm. There were also small lymphocytes with scant cytoplasm and deeply stained eccentrically placed nuclei and numerous mitotic figures. The history, clinical signs, and pathologic features were suggestive of avian lymphoid leukosis