The present study was conducted to investigate for the hematological test and treatment effect of cattle infected with theileriosis in Cheju area. The results were summarized as fellows 1. Symptom of cattle infected with theileriosis were lose of appetite, depression, jaundise, anemia and fever. 2. A postmortem sing of cattle infected with theileriosis were not observed exept for jaundise of subcutaneous, expansion of gallbladder. 3. In the hematological test results of cattle infected with theileriosis supposed lese then killed so far as RBC number of 1, 000, 000/mm and if treated with RBC number of 2, 000, 000/mm cattle was able to recovery 4. In the treatment of cattle infected with theileriosis recovered after 90 days of treatment and the precaution against a shock of blood transfusion were able to the control of injection time and blood qantity.