Three species of hemotropic mycoplasmas are known to infect cats worldwide, Mycoplasma haemofelis, “Candidatus Mycoplasma turicensis” and “Candidatus Mycoplasma haemominutum.” These organisms were previously known as Haemobartonella felis, but are now known to be mycoplasmas. Assays based on polymerase chain reaction technology are the most sensitive and specific diagnostic tests available for these organisms. M haemofelis is the most pathogenic species, and causes hemolytic anemia in immunocompetent cats. Other differential diagnoses for hemolytic anemia should be considered in cats testing positive for “Candidatus Mycoplasma turicensis” and “Candidatus Mycoplasma haemominutum,” because the presence of these organisms is not always associated with anemia. Blood from infected cats should be handled with care because of the potential zoonotic nature of hemoplasma infections. The treatment of choice for cats with clinical disease is doxycycline.