An unidentified Babesia of the domestic cat (Felis domesticus).

An unidentified Babesia was seen in a blood smear from a cat showing signs of anaemia. The cat responded to treatment with diminazene (Berenil). The morphology of the parasite is described and a comparison is made with other Babesia which have been described from the domestic cat and wild felids. This parasite most closely resembled B. herpailuri described from a jaguarundi in South America.