This study was made to inestigate the macroscopical and microscopical changes in calves which died and were slaughtered compulsorily from experimental theileriosis. In this study four splenectomized calves aged 6 to 8 months were used.

In the necropsy of the calves, the findings observed are these ; faded muco-se, jaundice in the connective tissue, hemorrhages in the kidneys, heart, mucose and serosa, enlargement in hte lymph nodes and liver, fullness in the urinary and gall bladders, oedema in the lung, ulcerations and hemorrhages in the abo-masum, aboundant bloody and gelatinous exudate in the abdominal cavity.

In the histopathological examination, the following findings were seen; hemorrgahes and necrosis with inflamatory reactions in lymph nodes, necrosis and ulcers in the abomasum, bronchopnumonia and oedema in the lung, interstitial nephritis in the kidneys, increase in the number of lymphocytes in the bone marrow and brain vessels, slight hemorrhages and hypremia in the brain and menings, cell filtration and hemorrhages in the tymus.