An immature female peregrine falcon (Falco peregrinus) was presented with a history of reduced appetite, gradual weight loss, and passing metallic-green urates. Survey radiographs revealed a slightly enlarged liver. Plasma biochemical analysis showed moderate to severe increases in concentrations of creatine kinase, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase, and hematologic analysis showed mild leukocytosis with severe lymphocytosis and mild monocytosis. The erythrocytes showed moderate hypochromasia with mild to moderate poikilocytosis and anisocytosis. Intracytoplasmic parasitic forms were observed in the erythrocytes, which were subsequently identified as Babesia shortii. It was estimated that the parasite was present in approximately 5.1% of the erythrocytes examined. The primary treatment consisted of the administration of imidocarb dipropionate administered at 5 mg/kq IM given once and repeated 1 week later. Supportive therapy was also provided. The falcon was discharged at the request of the owner 10 days after admission. One month after discharge, the falcon was presented for a general examination. At this stage, results of hematologic and plasma biochemical analysis values were all within reference ranges and no trace of parasitic forms could be found in the blood films examined.