A one-month old Holstein calf with clinical histories of diarrheal weekness and behavioural abnormality revealed clinical findings of anemia and dehydration. The red blood cells were $1.4{ imes} 10^{6}/{mu}l$ and packed red cell volume was 45%. A blood smear showed a large number of circulating Trypanosoma theileri. To treat Trypanosomiasisi the patient received once a daily oral dosage o$ulcorner$ 10 mg/kg of the Quinidine sulfate including transfusion (200 ml) for 3 days. After 2 weeks, the calf recovered body condition. These results suggest that Administration of Quinidine sulfate in trypanosomiasis may be a useful treatment approach.